Solved Set Hearts Color

How to set hearts color without giving effect
Like:
Wither->Hearts turn to black;
Poison->Hearts turn yellow-green;

It isn't controlled by PM

so the only way to control is give them effect, and cancelled the damage?

You can control this event.

https://github.com/PocketMine/PocketMine-MP/blob/master/src/pocketmine/entity/Effect.php#L211

so the solution is give them effect and cancelled EntityDamageEvent when cause is 1 and player have effect wither/poison

And CAUSE_MAGIC

Lol it's gonna be hard tho