msem-instigator

Discard a card: Warpblade Warrior gets +1/+1 and gains menace until end of turn. Activate only once each turn.

Menace, haste

Desecrate (When this creature enters, you may sacrifice an artifact or land.)
When Beastback Raider desecrates a permanent, discard your hand, then draw three cards.

At the beginning of your upkeep, exile the top card of your library. If a land card is exiled this way, add {R}{R}. You don't lose this mana as steps and phases end this turn. Otherwise, you may cast that card this turn.

Haste
Desecrate (When this creature enters, you may sacrifice an artifact or land.)
When Bloodboil Harlequin desecrates a permanent, up to two target creatures can't block this turn.

Brazen Sacrilege deals 2 damage to any target. Until end of turn, if a red source you control would deal damage to that player or to that permanent's controller, it deals that much damage plus 1 instead.

When Curio Pavilion enters, create two Treasure tokens. (They're artifacts with “{T}, Sacrifice this artifact: Add one mana of any color.”)
Whenever an artifact you control leaves the battlefield, you may discard a card. If you do, draw a card.

Dreamchaser Djinni attacks each combat if able.

Chosen one ({W}{U}{B}{R}{G}: Transform this permanent.)
At the beginning of combat on your turn, create a 1/1 red Warrior creature token with haste. That token attacks this combat if able.

Flying
At the beginning of combat on your turn, create a 5/5 red Dragon creature token with flying and haste. That token attacks this combat if able.

Flying, haste
Whenever Emissary of Antiquity deals combat damage to a player, you may cast an instant or sorcery spell with mana value 3 or less from your hand without paying its mana cost.

Choose one —
• Creatures you control get +2/+0 until end of turn.
• Creatures your opponents control can't block creatures with less power this turn.

Desecrate (When this creature enters, you may sacrifice an artifact or land.)
When Encrusted Sahalia desecrates a permanent, it deals 3 damage to target player.

Create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)
Draw a card.

Chosen one ({W}{U}{B}{R}{G}: Transform this permanent.)
Whenever Fervent Ensign attacks, add {R} at the beginning of your next main phase.

Flying
Whenever Archon of Inspiration attacks, add three mana in any combination of colors at the beginning of your next main phase.

Fierce Contempt deals 6 damage to target creature.

When Globule of Turmoil enters or leaves the battlefield, up to one target creature can't block this turn.
{2/R}, {T}, Sacrifice Globule of Turmoil: Draw a card.

When Hand of Fury enters, it gets +2/+2 and gains haste until end of turn.
At the beginning of your upkeep, if your fealty to Mountains is five or greater, transform Hand of Fury. (Each Mountain you control counts towards your fealty to Mountains.)

At the beginning of combat on your turn, target creature gets +1/+1 and gains haste until end of turn.

Destroy target colorless nonbasic permanent. Harsh Erosion deals 2 damage to that permanent's controller.

Heat Ray deals X damage to target creature.

Haste
Whenever Herald of the Humble deals combat damage to a player, that player reveals the top card of their library. If it's a nonland card with mana value 3 or less, they may cast it without paying its mana cost.

Tap an untapped Desert you control: Hostile Atmosphere deals 1 damage to any target.

Enchant creature
When Impish Delights enters, draw a card.
Enchanted creature gets +2/+0.