msem-instigator

Whenever you cast a noncreature spell, you may have target player mill two cards. Then if a player has twenty or fewer cards in their library, put a +1/+1 counter on Living Atrocity.

Instant, sorcery, and legendary spells you cast cost {1} less to cast.

Other Pirates and Rogues you control get +1/+0.
Whenever you attack with three or more Pirates and/or Rogues, tap target creature.

Flying, vigilance
When Manafly enters, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.

Flash
You may cast Angel and Nephilim spells as though they had flash.

Flash
When Master Echomage enters, you may cast target instant or sorcery card from your graveyard with mana value X or less without paying its mana cost, where X is the number of Wizards you control. Exile that card instead of putting it into your graveyard as it resolves.

Whenever Merfolk Vandal deals combat damage to a player, you may pay {U}. If you do, transform it.

Flash (You may cast this spell any time you could cast an instant.)
Flying (This creature can't be blocked except by creatures with flying or reach.)

Whenever you cast your first instant or sorcery spell each turn, create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

Whenever Path Lighter deals combat damage to a player, it explores. (Reveal the top card of your library. Put it into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then you may put that card in your graveyard.)

When Peddler of Commonwares enters, you may draw a card. If you do, discard a card.

{2}{U}: Target creature can't be blocked this turn.

When Practiced Sorcerer enters, return target noncreature, nonland card from your graveyard to your hand.

{1}, {T}: Copy target activated or triggered ability you control. You may choose new targets for the copy.
{3}{U}, {T}: Copy target spell you control. You may choose new targets for the copy. (A copy of a permanent spell becomes a token.)

When Raving Brigand enters, forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)
Whenever you sacrifice an Omen, target player mills three cards.

{7}{U}: Tap up to three target nonland permanents. This ability costs {2} less to activate if you control a legendary creature.

When Sandborn Mage enters, you may return target instant or sorcery card from your graveyard to your hand.
Mirage {2}{U}{U} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

When Scaled Lurker enters, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.

Whenever a creature you control enters, if it wasn't cast from your hand, you may mill a number of cards equal to its mana value. If you do, you may return a noncreature card milled this way from your graveyard to your hand.

Encourage ({T}: Another target creature you control gets +1/+1 until end of turn. Encourage only as a sorcery.)
Whenever Serul Cove Escort encourages a creature, that creature gains flying until end of turn.

Prowess
{T}: Catalyze, then catalyze again. Activate only if Sigil Slinger's power is 5 or greater. (The next spell you cast this turn costs {2} less to cast.)

Flash (You may cast this spell any time you could cast an instant.)
When Silk Crane Adept enters, target creature gains hexproof until end of turn.

{2}{U}, {T}: Look at the top card of your library. If it's a Scout card or a card with an Adventure, you may reveal it and draw a card.

Skysworn Aspirant has flying as long as it's embattled. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

Prowess
Whenever you cast a noncreature spell, you may mill two cards.