Nicholas, Reborn Raider

Menace
Whenever Nicholas, Reborn Raider attacks,
double its power and toughness until end of turn.
If Nicholas, Reborn Raider would die, instead
exile it with X seed counters equal to its power.
At the beginning of each upkeep, if Nicholas is
exiled with a seed counter on it, remove a seed
counter from it.
Then if Nicholas has no seed counters on it,
return it to the battlefield.