Mantis, Apex Predator

First Strike, Double Strike

When this creature destroys another creature, this creature gains +1/+1

{2}{x}: Exile {x}creatures you control, Mantis, Apex Predator gains +X/+X

Apex Predator: When this creature does combat damage to
a creature, that creature gets -X/-X, where equals its strength, if a creature were to be destroyed this way, exile instead.