Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Bhaal's Invoker

Scorching Ray — {8}: Bhaal's Invoker deals 4 damage to each opponent.

Valakut Invoker

{8}: Valakut Invoker deals 3 damage to any target.

Welder Automaton

{3}{R}: Welder Automaton deals 1 damage to each opponent.

Essence Warden

Whenever another creature enters, you gain 1 life.

Presence of Gond

Enchant creature
Enchanted creature has "{T}: Create a 1/1 green Elf Warrior creature token."

Snarling Gorehound

Menace
Whenever another creature you control with power 2 or less enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Molten Gatekeeper

Whenever another creature you control enters, Molten Gatekeeper deals 1 damage to each opponent.
Unearth {R} ({R}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Grinning Ignus

{R}, Return Grinning Ignus to its owner's hand: Add {C}{C}{R}. Activate only as a sorcery.

Skyshroud Elf

Scalding Devil

{2}{R}: Scalding Devil deals 1 damage to target player or planeswalker.

Midnight Guard

Whenever another creature enters, untap Midnight Guard.

Goblin Anarchomancer

Each spell you cast that's red or green costs {1} less to cast.

Flamewave Invoker

{7}{R}: Flamewave Invoker deals 5 damage to target player or planeswalker.

Thornscape Familiar

Red spells and white spells you cast cost {1} less to cast.

Ninth Bridge Patrol

Whenever another creature you control leaves the battlefield, put a +1/+1 counter on Ninth Bridge Patrol.