Mairsil, the Pretender

The exiled cards remain exiled with cage counters when Mairsil leaves the battlefield. If Mairsil returns to the battlefield, it will see all of those exiled cards with cage counters on them.

Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keyword abilities (such as equip) are activated abilities and will have colons in their reminder text. Mairsil won't gain triggered abilities (which start with "when," "whenever," or "at").

If an activated ability of a card in exile with a cage counter on it references the card it's printed on by name, treat Mairsil's instance of that ability as though it referenced Mairsil by name instead. For instance, if Mairsil exiles Magus of the Mind, the cost to activate the ability includes sacrificing Mairsil, not sacrificing Magus of the Mind.