Whenever Ashcoat attacks or blocks, other Rats you control get +X/+X until end of turn, where X is the number of Rats you control.
At the beginning of your end step, you may mill four cards. If you do, return up to two Rat creature cards from your graveyard to your hand. (To mill a card, put the top card of your library into your graveyard.)
You choose which Rat creature cards to return to your hand as the last ability resolves. You may choose Rat creature cards milled with this ability.
2 Dec 2022
The value of X is locked in as the first ability resolves. The bonus it grants won't change after that point, even if the number of Rats you control does.