"All five bosses, back to back, no waiting and no mercy."<ref name="indiebox">IndieBox instruction manual</ref>
The premise is simple - fight Embryo, Vespula, Justice, Venom and Medulla back-to-back, in that order. This takes about 10 minutes for a typical successful run, though sub-6 minute times are possible. The par time is 12 minutes.
As soon as a boss is beaten, the next one immediately spawns in. The arena opens up for Venom, then closes again for Medulla. Score, Combo, weapon reinforcement level, and any Batteries or Powerups on the ground are conserved between boss changes.
The run ends when you run out of Battery or when Medulla's Aethersphere phase is defeated. Only successful attempts receive a leaderboard score and a Rank. Players are ordered on the leaderboard by score only.
Four things are important for scoring high in Boss Rush:
- Finishing quickly. This is necessary for the quick kill bonus on each phase, as well as having a high completion time bonus.
- Holding Combo. This is obvious, as it determines your score multiplier when defeating each boss section. When aiming for score, dropping Combo at any time is an instant restart. You can afford to drop combo in the Aethersphere or during Vespula's wasp sections with not much penalty, but that's about it.
- Not getting knocked down. Getting knocked down incurs a significant time loss, a direct Score penalty, breaks your Combo, and resets your weapon power. Unlike Daily/Infinity Drive, knockdown score penalty is not capped at 100k, so you can potentially lose millions on a single down.
- Surging Justice with his own head in his 3rd phase.
- Surging White Justice with his own head when he appears during the Medulla fight.
- Surging Aethersphere mobs.
It should be noted that your character gains control slightly earlier than in the normal Embryo fight. This gives you extra time to reposition or Weapon Swap to your secondary. Consider using this time to move up and above Embryo in order to collect weapon power.
|Boss / Phase||Ideal total score||Notes|
|Embryo||311,000 + 1000*10 = 321,000||Same as the regular Embryo fight, except you get a Battery afterwards. It's possible to use Vespula Wasps to build your combo up to 10x before collecting it.|
|Vespula||1,370,150 + 1000*10 = 1,380,150||Same as the regular Vespula fight, except you get a Battery after the final phase.|
|Justice||8,480,000||Already calculated out in Justice#Overview.|
|Venom||24000x10 + 6500*10*4 + 30000*10 + 24000*10*2 + 6500x10x8 + 30000x10 + 30000x10 + 22500x10 + 1000*10*8 = 2,705,000||Each term represents the 8 Venom phases but with a 10x multiplier, plus 8 Batteries.|
|Medulla Phases 1-5||135,000*10 + 135,000*10 + 135,000*10 + 135,000*10 + 135,000*10 + 1000*10*5 = 6,800,000||Quick kill bonus, 10x multiplier, 5 Batteries.|
|Medulla Phase 6||2000*10 + 2000*10*1.5 + 135,000*10*1.5 + 1000*10 = 2,085,000||Quick kill bonus, killing both heads, Surging second head with White Justice himself, Battery|
|Medulla Phase 7||150,000*10 = 1,500,000||Quick kill bonus. No Battery after this phase.|
|Aethersphere||54800*10*1.5 = 822,000||Surging every single mob in the Aethersphere. 54,800 is the combined base score of every mob.|
|With time bonus||24,093,150 + 640,000 = 24,733,150||An amazing time to finish with both Justice surges would be about 5:20.|
|I Am Become Death||Complete Boss Rush mode||Boss Rush unlocks after you beat Medulla. Cactus is not a bad choice for the job.|