Bioelectric Krasis

Evolve (Whenever a creature enters the battlefield
under your control, if that creature has greater power
or toughness than this creature, put a +1/+1 counter
on this creature.)
Whenever one or more +1/+1 counters are put
on a creature you control, that creature may fight another target creature.
"Our latest results have been... shocking."
-Gulistan, Simic Biomancer