Dreadhorde Arcanist

Trample
Whenever Dreadhorde Arcanist attacks, you may cast target instant or sorcery card with mana value less than or equal to Dreadhorde Arcanist's power from your graveyard without paying its mana cost. If that spell would be put into your graveyard, exile it instead.

Inti, Seneschal of the Sun

Whenever you attack, you may discard a card. When you do, put a +1/+1 counter on target attacking creature. It gains trample until end of turn.
Whenever you discard one or more cards, exile the top card of your library. You may play that card until your next end step.

Break Out

Look at the top six cards of your library. You may reveal a creature card from among them. If that card has mana value 2 or less, you may put it onto the battlefield and it gains haste until end of turn. If you didn't put the revealed card onto the battlefield this way, put it into your hand. Put the rest on the bottom of your library in a random order.