Acquired Mutation

If a player has fewer cards remaining in their library than the number of rad counters they have when the triggered ability resolves, they’ll mill as many cards as they can.

Any effects (such as proliferate) that interact with counters a player gets, has, or loses can interact with rad counters.

Being goaded isn’t an ability the creature has. Once it’s been goaded, it must attack as detailed above even if it loses all abilities.

Rad counters are a kind of counter that a player may have. They’re not associated with any specific permanents.

The cards are milled all at once, which means abilities that trigger “whenever one or more nonland cards are milled” will trigger exactly once as long as at least one nonland card was milled.

If, during a player’s declare attackers step, a creature that player controls that’s been goaded is tapped, is affected by a spell or ability that says it can’t attack, or hasn’t been under that player’s control continuously since the turn began (and doesn’t have haste), then it doesn’t attack. If there’s a cost associated with having a creature attack a player, its controller isn’t forced to pay that cost, so it doesn’t have to attack that player.