Lost in Thought

{1}{U} · Enchantment — Aura

Enchant creature Enchanted creature can't attack or block, and its activated abilities can't be activated. Its controller may exile three cards from their graveyard for that player to ignore this effect until end of turn.

Motor: se resuelve a mano

Rulings (2)

Activated abilities contain a colon. They’re generally written “[Cost]: [Effect].” Some keywords are activated abilities and will have colons in their reminder text.
Wizards of the Coast · 2016-06-08
You can take the “exile three cards” action any time you have priority without using the stack.
Wizards of the Coast · 2004-10-04