Runeblazer Fiend

Instant and sorcery spells you cast cost {1} less to
cast.
Delirium — Whenever you cast an instant or
sorcery spell, if there are four or more card types
among cards in your graveyard, you may exile the
top card of your library. If you do, you may play
that card if it doesn't share a card type with a
card in your graveyard. If you don't exile a card
or play a card exiled with this ability, Runeblazer
Fiend deals 1 damage to any target.