what about an ability like this, let's call it
SPROUT as an active ability ability. Basically means that if the antillon manage in doing a successful attack, he gets -0/-1 but in the following turn it can activate sprout, that's to say he can create another antillon with same values, that's to asay 2/2 after the attack. You may choose to not click to activate sprout, but at 0 resistance this creature will die anyway. I leave to you debate on which should be the copst of sprout, maybe 1
?
card text:
"When the antillon do a successful attack, it gets 0/-1 and it gains sprout.
Sprout: create an exact copy of the antillon"
With sprout i mean something different from twin universe, since also special abilities can be duplicated. So to not create confusion having a creature with two different abilities, sprout cost should be 0, automatic after a successful attack.