Phylactery Lich

If you control no artifacts as Phylactery Lich enters the battlefield, its first ability won’t do anything. As soon as it enters the battlefield, its last ability will trigger (unless you control some other permanent with a phylactery counter on it) and you’ll have to sacrifice it.

If Phylactery Lich and an artifact are entering the battlefield under your control at the same time, you can’t put a phylactery counter on that artifact. You must choose an artifact you control that’s already on the battlefield.

Phylactery Lich’s last ability is a “state trigger.” Once a state trigger triggers, it won’t trigger again as long as the ability is on the stack. If the ability is countered and the trigger condition is still true, it will immediately trigger again.