Hmmm so according to your calculation its just 7% needed to kill it, so you will hit around like 2% maximum for the first 2 transformations right ? (When you dont need to 'feed' him) Hmmm its kinda hard to predict what % i hit already.
I assume that it's good to hit him no more than 10% of his max health.
Since most SCs are now run with a dex stat buffer & at least 1 more katar (If not 2), it's very hard to kill him without feeding, because the damage dealt at a time is so high.
The most common way is to let 1 single player hit it (katar/scout/bc/gun user prefered), because more people means more possibilities to exceed the HP calculation. However, many players are so aggressive that they might think you're underestimating them
So yeah, I suggest you take some time to run with friends first to do some calculation on gears and tactics.
I personally change to low damage gears while fighting against Gloopy in order to avoid that.
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Update 7.15.2015
- Added revised Gloopy's Room map
- Added #2 tip
Edited by thetrangdamvn, 14 July 2015 - 07:24 PM.