Lutri, the Spell Scavenger

Companion - Your starting deck has 8 unique instant and/or sorcery spells with CMC 5 or greater.
Whenever Lutri, the Spell Scavenger enters the battlefield, put a retrieve counter on up to 4 instant and/or sorcery spells with CMC 5 or greater in graveyards.
You can cast spells with retrieve counters on them any time you could cast an instant, spending mana as though it was mana of any color.