Harvargen, Soul Guide

Flying, Vigilance

Other spirits you control get +1/+1.

Whenever a spirit you control would deal damage to an opponent, that opponent exiles the top four cards from their library and you may cast a non-land card as long as it is exiled this way. You may cast that card as long as it remains exiled, and you may spend mana as though it were mana of any color to cast that spell.