Ronar, Riftborn Prodigy

Whenever you cast an instant or sorcery spell with
mana value 4 or less, add {r} and exile the top 2
cards of your library. You may cast these cards
until the end of your next turn.
Whenever you cast an instant or sorcery spell with
mana value 5 or greater, Ronar, Riftborn Prodigy
deals 2 damage to any target.
At the beginning of your end step, if you cast 5
or more instant or sorcery spells this turn,
transform Ronar, Riftborn Prodigy