Berserkers' Onslaught

Attacking creatures you control have double strike.

Flameshadow Conjuring

Whenever a nontoken creature you control enters, you may pay {R}. If you do, create a token that's a copy of that creature. That token gains haste. Exile it at the beginning of the next end step.

Nature's Will

Whenever one or more creatures you control deal combat damage to a player, tap all lands that player controls and untap all lands you control.

Blaster, Morale Booster

Modular 3
{X}, {T}: Move X +1/+1 counters from Blaster onto another target artifact. That artifact gains haste until end of turn. If Blaster has no +1/+1 counters on it, convert it. Activate only as a sorcery.

Blaster, Combat DJ

More Than Meets the Eye {1}{R}{G} (You may cast this card converted for {1}{R}{G}.)
Other nontoken artifact creatures and Vehicles you control have modular 1. (They enter with an additional +1/+1 counter on them. When they die, you may put their +1/+1 counters on target artifact creature.)
Whenever you put one or more +1/+1 counters on Blaster, convert it.

Blaster, Combat DJ // Blaster, Morale Booster

Unnatural Growth

At the beginning of each combat, double the power and toughness of each creature you control until end of turn.

Guardian Project

Whenever a nontoken creature you control enters, if it doesn't have the same name as another creature you control or a creature card in your graveyard, draw a card.

Fiery Emancipation

If a source you control would deal damage to a permanent or player, it deals triple that damage to that permanent or player instead.

Eidolon of Blossoms

Constellation — Whenever Eidolon of Blossoms or another enchantment you control enters, draw a card.

Bello, Bard of the Brambles

During your turn, each non-Equipment artifact and non-Aura enchantment you control with mana value 4 or greater is a 4/4 Elemental creature in addition to its other types and has indestructible, haste, and "Whenever this creature deals combat damage to a player, draw a card."

Molten Echoes

As Molten Echoes enters, choose a creature type.
Whenever a nontoken creature you control of the chosen type enters, create a token that's a copy of that creature. That token gains haste. Exile it at the beginning of the next end step.