Firstly, excellent that you got that far. I was uncertain whether anyone would in this build.
Endgame isn’t quite a win – it’s the last phase, which has a few special rules that can be read on its tooltip. I’ll have to add some more fanfare to phase transitions so that’s clear. And explain the mechanic in a popup the first time it happens.
You’re right that those symbols are reactions. I’ll try to place those so they’re more on top of the HP bar, so it’s easier to see them regardless of the background. And mention them in the tutorial.
(The rest is noted)