Onimusha Boss Speedkill Guide: Every Boss Fast Kill Strategy & Optimal Burst Combos

Speedkill Fundamentals and Damage Optimization

Boss speedkilling is the art of defeating bosses as quickly as possible using optimized damage rotations, exploit setups, and perfect execution. A speedkill is not just a fast kill -- it is the theoretically fastest possible kill given the game's mechanics.

What Counts as a Speedkill?

A speedkill is typically defined as killing a boss in under 30 seconds, though the exact threshold varies by boss. Some early bosses can be killed in under 10 seconds with the right setup, while late-game bosses might take 45-60 seconds even with perfect play. The community tracks speedkill records for each boss separately.

Damage Multiplier Stacking

The foundation of every speedkill is stacking as many damage multipliers as possible before the burst. The optimal stack is:

• Oni Awakening: 1.5x damage
• Attack Potion: 1.3x damage
• Crimson Amulet (HP > 80%): 1.1x damage
• Oni Costume: 1.2x damage (if available)
• Elemental weakness: 1.5x damage
• Weapon level 5: base damage maximized

Total multiplier: 1.5 x 1.3 x 1.1 x 1.2 x 1.5 = 3.86x damage. With a max-level weapon dealing 200 base damage per hit, this becomes 772 damage per hit. A full burst combo dealing 15 hits would deal 11,580 damage -- enough to kill most mid-game bosses in one rotation.

Pre-Fight Preparation

Before entering a boss arena for a speedkill:

1. Fill Oni gauge to max (6 bars)
2. Fill MP to max (100)
3. Use Attack Potion (lasts 3 minutes)
4. Equip optimal damage accessories
5. Change to optimal weapon for the boss's weakness
6. Heal to full HP (for Crimson Amulet bonus)
7. Position at the optimal starting spot

All buffs should be active before the boss fight starts. Wasting time buffing during the fight adds seconds to your time.

Optimal Burst Combo Rotations

The core of any boss speedkill is the burst combo -- a sequence of attacks that deals the maximum possible damage in the minimum amount of time. Here are the highest-DPS rotations in the game.

Standard Burst (No Magic)

For bosses where you want to save MP or magic is not effective:

Rotation: Light x3 -> Heavy (launch if applicable) -> Air Light x3 -> Air Heavy (slam) -> Land -> Dodge Cancel -> Repeat

This air combo rotation deals approximately 1,200 damage per cycle with a max-level weapon and all buffs, and takes about 4 seconds. DPS: ~300. Good for sustained damage when you have lots of Oni gauge but limited MP.

Magic Burst (High MP)

For bosses where you want maximum burst damage:

Rotation: Light x3 -> Magic Cancel (Fire Pillar) -> Magic Cancel (Blizzard) -> Magic-to-Attack Cancel (Heavy) -> Light x2 -> Dodge Cancel -> Repeat

This magic-cancel rotation deals approximately 2,000 damage per cycle and takes about 3 seconds. DPS: ~667. This is the highest-DPS rotation in the game but consumes MP rapidly (about 40 MP per cycle). With 100 max MP, you can do 2 full cycles before running out.

Issen Burst (High Skill)

For bosses with Issen-able attacks, the fastest kills use Issen repeatedly:

Rotation: Provoke boss attack -> Issen the attack -> Immediately position for next attack -> Issen again -> Repeat

Each successful Issen deals 10-15% of the boss's max HP in damage (during Awakening, this doubles to 20-30%). If you can Issen consistently, you can kill some bosses in 3-5 successful Issens. The limiting factor is how quickly the boss attacks -- you cannot Issen faster than the boss attacks.

Early Boss Speedkill Strategies (Chapters 1-4)

Early bosses are the easiest to speedkill because they have low HP and simple patterns. With NG+ gear, you can kill some of them in under 10 seconds.

Demon Samurai (Chapter 1 Boss)

Target Time: Sub-15 seconds (NG+), Sub-30 seconds (NG)

Strategy: Start with Oni Awakening already active (if NG+). Run directly at the boss and start a magic burst combo. The boss will try to attack you, but your attacks should stun-lock it if you are fast enough. Use the standard magic cancel rotation. If the boss breaks out of stun, Issen its counter attack. With full buffs and a level 5 weapon, you can kill this boss in 2-3 burst cycles.

World record tip: If you position perfectly, you can trap the boss against the wall and stun-lock it for the entire fight. This eliminates the need to dodge or Issen anything.

Giant Centipede (Chapter 2 Boss)

Target Time: Sub-20 seconds (NG+)

Weakness: Fire (2.0x damage)

Strategy: This boss is a speedkill dream because it has a clear vulnerability phase and a huge weakness to fire. Start with fire weapon (Enryuu) and full buffs. Attack the head until the boss burrows, then position for its re-emergence. When it emerges, use fire magic + weapon attacks for maximum burst. The Enryuu's fire element combined with the 2.0x weakness means each hit deals double damage, melting this boss very quickly.

Twin Warriors (Chapter 3 Boss)

Target Time: Sub-25 seconds (NG+)

Strategy: This is a two-boss fight, which makes speedkilling trickier. The optimal strategy is to focus fire on one boss at a time. Use AOE attacks to damage both simultaneously, but focus your single-target damage on the left one first (it has slightly less HP). Use wide sweeps and magic to build stun on both. When one dies, switch to the other. The key is not letting either boss get attacks off -- constant pressure with fast combos keeps them stunned.

Phantom Knight (Chapter 4 Boss)

Target Time: Sub-30 seconds (NG+)

Weakness: Lightning (1.5x damage)

Strategy: Use the Raizen (lightning katana) for this fight. The Phantom Knight has a teleport move that makes it hard to pin down, but if you anticipate the teleport you can be ready to attack when it reappears. The pattern is always: teleport behind you -> slash. Turn around immediately when it teleports and start your combo. Use Issen on the slash attack if you mess up the timing. With good prediction, you can keep the pressure on and kill it before it teleports too many times.

Mid-Boss Speedkill Strategies (Chapters 5-8)

Mid-game bosses have more HP and more complex patterns, making speedkills more challenging. These require good knowledge of boss patterns and solid execution.

Spider Witch (Chapter 5 Boss)

Target Time: Sub-35 seconds (NG+)

Weakness: Fire (1.5x damage)

Strategy: The Spider Witch summons minions, which slows down speedkills because you have to deal with the spiders. The speedkill strategy is to ignore the minions entirely and focus all damage on the witch. Use the fire longsword (Enryuu) for the 1.5x weakness bonus. Stay in melee range and attack constantly -- the witch has trouble attacking when you are right next to her. Use Oni Awakening at the start and burn her down before she summons too many spiders.

Pro tip: If you position yourself between the witch and the spider spawn points, the spiders will have to path around you to attack, giving you more time to damage the witch.

Stone Golem (Chapter 6 Boss)

Target Time: Sub-40 seconds (NG+)

Weakness: Lightning (1.5x damage)

Strategy: The Stone Golem is slow but has a lot of HP and high defense. The speedkill strategy revolves around the ground slam attack, which leaves the golem vulnerable for 3 full seconds. Provoke the ground slam by staying at range, then dodge it and run in for a full burst combo. During the vulnerability window, use your highest-DPS rotation (magic cancel). Each ground slam gives you about 3 seconds of free damage, which is enough for one full magic burst cycle dealing ~2,000 damage.

With 5 ground slam opportunities (one every 8 seconds or so), you can deal 10,000+ damage in 40 seconds. That is enough to kill the golem even on hard mode.

Oni Warrior (Chapter 7 Boss)

Target Time: Sub-45 seconds (NG+)

Weakness: Dark (1.5x damage, if you have dark weapon)

Strategy: The Oni Warrior is one of the hardest bosses to speedkill because of his counter-attack mechanic (he counters any combo longer than 3 hits). The speedkill strategy is to use Issen on his dash attack repeatedly. The dash attack has a long tell and is easy to Issen once you have the timing down. Each Issen deals 10-15% of his HP (20-30% during Awakening), so 4-5 successful Issens kill him.

The key to speed is positioning yourself so he uses the dash attack as often as possible. Stay at mid-to-long range and he will dash at you constantly. Each cycle (dash -> Issen -> reposition) takes about 6-8 seconds, so the whole fight is 30-40 seconds if you do not miss any Issens.

Late Game and Final Boss Speedkills

Late game bosses have the most HP and the most complex mechanics. Speedkilling these requires both mastery of mechanics and careful planning.

Dark Priest (Chapter 9 Boss)

Target Time: Sub-50 seconds (NG+)

Weakness: Light/Holy (1.5x damage, rare element)

Strategy: The Dark Priest spends a lot of time teleporting and summoning minions, which slows down speedkills. The speedkill strategy is to use ranged attacks and magic to hit him during his brief stationary periods (when he is channeling spells). Use homing magic that tracks him even when he teleports. When he summons minions, use AOE magic to clear them quickly and build Oni gauge.

The fastest kills use the Demon Sword (if you have it from NG+ post-game) because its dark element bypasses some of the priest's defense. The priest has high magic resistance but lower physical resistance, so physical damage is actually better than magic despite him being a caster.

Castle Lord (Chapter 10 Boss)

Target Time: Sub-45 seconds (NG+)

Weakness: Wind (1.5x damage)

Strategy: The Castle Lord has a large sword and slow, powerful attacks. His attacks are all Issen-able, making him a prime candidate for Issen-based speedkills. His most Issen-friendly attack is the overhead slash, which has a very long windup and clear tell. You can reliably Issen this attack every time.

During Phase 2 (below 50% HP), he gains a multi-hit combo. This is harder to Issen but still possible if you focus on the first hit of the combo. Use Oni Awakening during Phase 2 to maximize damage from each Issen. With perfect Issen execution, you can kill him in 6-7 Issens over 40-45 seconds.

Final Boss

Target Time: Sub-90 seconds (NG+), Sub-120 seconds (NG)

Weakness: Varies by phase (see below)

Strategy: The final boss has three phases, each with different weaknesses and patterns.

Phase 1 (100-66% HP): Weak to lightning. Attack the hands when they rest on the ground. Use fast attacks to build stun. This phase should take 20-25 seconds with full buffs.

Phase 2 (66-33% HP): Weak to fire. Adds spawn periodically -- use AOE to clear them. Boss has more attack patterns but still has clear vulnerability windows. This phase takes 25-35 seconds.

Phase 3 (33-0% HP): No elemental weakness. Rapid combos and AOE attacks. This is the hardest phase. Save your Oni Awakening for this phase and use Issen on the combo attacks. The vulnerability window after the 4th attack of the combo is your main damage opportunity. This phase takes 35-45 seconds.

Total time: 80-105 seconds for a good speedkill. The world record is under 70 seconds using advanced techniques and glitches.

Issen-Based Speedkill Techniques

For bosses with Issen-able attacks, Issen-based speedkills are often the fastest because Issen deals percentage-based damage to bosses. Here is how to optimize Issen speedkills.

Why Issen Is Good for Speedkills

Against bosses, Issen deals a percentage of the boss's max HP (approximately 10-15% per Issen on normal, 15-20% on hard mode, doubled during Oni Awakening). This means Issen damage scales with boss HP -- the more HP the boss has, the more damage each Issen deals. For bosses with very high HP, Issen can actually deal more damage per second than combo-based attacks.

The Issen Loop Strategy

The Issen loop is: (1) Position to provoke a specific boss attack, (2) Issen the attack, (3) Reposition to provoke the same attack again, (4) Repeat. The key is finding a position and distance that makes the boss use the same Issen-able attack every time.

For most bosses, the optimal distance for Issen loops is mid-range -- close enough that the boss wants to attack you, but far enough that it uses its ranged or dash attack (which is usually easier to Issen than close-range combos).

Oni Awakening + Issen Combo

The most damaging technique in the game is Issen during Oni Awakening. Awakening doubles Issen damage, so each Awakened Issen deals 20-30% of a boss's max HP. If you can land 3-4 Awakened Issens, you kill most bosses in just a few hits.

To set this up: (1) Fill Oni gauge before the fight, (2) Activate Awakening at the start of the fight, (3) Immediately provoke an Issen-able attack, (4) Issen it for massive damage, (5) Repeat for the duration of Awakening.

With a 20-second Awakening (extended by Oni Costume to 26 seconds), you can usually land 4-5 Issens, dealing 80-150% of the boss's HP in damage. This is why some bosses can be killed in under 10 seconds with perfect setup.

Common Issen Speedkill Mistakes

1. Wrong positioning: If you are too close, the boss uses close-range attacks that are harder to Issen. If too far, the boss might not attack at all.

2. Missing the first Issen: The first Issen of a speedkill attempt is the most important because it sets the rhythm. If you miss it, the whole attempt falls apart.

3. Forgetting to reposition: After each Issen, you need to move back to the optimal position for the next loop. If you stay in place, the boss might use a different attack.

Speedkill Practice Tips and Progression

Learning boss speedkills takes time and practice. Here is how to approach it systematically and improve quickly.

Start with Easy Bosses

Begin your speedkill practice with the easiest bosses: the Chapter 1 Demon Samurai and the Chapter 2 Giant Centipede. These bosses have simple patterns and low HP, so you can practice the fundamentals without getting frustrated. Once you can consistently kill these in under 30 seconds, move to harder bosses.

Break Down Each Boss

For each boss you want to speedkill, study it systematically:

1. Watch speedkill videos to see what the optimal strategy looks like
2. Learn all of the boss's attacks and which ones are Issen-able
3. Find the optimal position and distance for provoking the right attack
4. Practice the burst rotation on regular enemies first
5. Attempt the speedkill, starting with a relaxed target time
6. Gradually lower your target time as you get more consistent

Record and Review

Record your speedkill attempts and review them afterward. Look for places where you lost time: missed Issens, slow positioning, wrong attack choices, buff management mistakes. It is often helpful to compare your runs to world record runs and see where the time difference comes from.

Realistic Progression Timeline

0-5 hours of practice: Can speedkill early bosses in 30-60 seconds. Consistency: 50% success rate.

5-15 hours of practice: Can speedkill most bosses in target times. Consistency: 70-80% success rate on easy bosses, 40-60% on hard ones.

15-30 hours of practice: Near-world-record times on most bosses. Consistency: 80%+ on easy bosses, 60-70% on hard ones.

30+ hours: World record level. Consistently achieving times close to or equal to the best players.

Remember: speedkilling is about perfection, and perfection takes time. Do not get discouraged if you struggle at first -- every speedkill master started where you are.