Infesting Radroach

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.

Keep track of how many rad counters each player has. Potential ways to track this include writing them down on paper or using dice, but any method that is clear and mutually agreeable is fine.

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.

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

If Infesting Radroach is milled at the same time an opponent mills a nonland card (for example, because of the activated ability of Raul, Trouble Shooter), Infesting Radroach's ability will trigger.