Thermo-Alchemist

Defender
{T}: Thermo-Alchemist deals 1 damage to each opponent.
Whenever you cast an instant or sorcery spell, untap Thermo-Alchemist.

Impact Tremors

Whenever a creature you control enters, Impact Tremors deals 1 damage to each opponent.

Gemhide Sliver

All Slivers have "{T}: Add one mana of any color."

Karmic Guide

Flying, protection from black
Echo {3}{W}{W} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When Karmic Guide enters, return target creature card from your graveyard to the battlefield.

Rocco, Cabaretti Caterer

When Rocco, Cabaretti Caterer enters, if you cast it, you may search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.

Faeburrow Elder

Vigilance
Faeburrow Elder gets +1/+1 for each color among permanents you control.
{T}: For each color among permanents you control, add one mana of that color.

Temur Sabertooth

{1}{G}: You may return another creature you control to its owner's hand. If you do, Temur Sabertooth gains indestructible until end of turn.

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Goblin Bombardment

Sacrifice a creature: Goblin Bombardment deals 1 damage to any target.

Felidar Guardian

When Felidar Guardian enters, you may exile another target permanent you control, then return that card to the battlefield under its owner's control.

Avacyn's Pilgrim

Village Bell-Ringer

Flash (You may cast this spell any time you could cast an instant.)
When Village Bell-Ringer enters, untap all creatures you control.

Karametra's Acolyte

{T}: Add an amount of {G} equal to your devotion to green. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)