msem-instigator

[+1]: Up to two target creatures you control each get +1/+0 and gain first strike until end of turn.
[0]: You may sacrifice a creature. If you do, Shala Na, Urshadi Apostate deals 3 damage to any target.
[–3]: Discard your hand, then draw three cards.

When Sandbluff Assailant enters, it deals 1 damage to target player or planeswalker.

Prowess
{1}: Shifting Dweller gets +1/-1 until end of turn.

Whenever you cast a noncreature spell, Novice Pyromancer deals 1 damage to target player or planeswalker.

When Arpechian Groundskeeper enters, rouse 1. (Put a +1/+1 counter on a permanent you control. If it isn't a creature, tap it and it becomes a 0/0 creature in addition to its other types.)
Remove a +1/+1 counter from Arpechian Groundskeeper: Draw a card.

Reach
Whenever Nanowrought Vanguard attacks, put a +1/+1 counter on each enchantment creature you control.

Sacrifice Voice of Ambition: Target creature gets +2/+1 until end of turn.

Choose target instant spell, sorcery spell, activated ability, or triggered ability. Create a Function token with its effects. Then you may pay {1}{U}. If you do, counter that spell or ability. (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell. A spell's effects includes added functions.)

Battalion — Whenever Battleborn Brute and at least two other creatures attack, Battleborn Brute gets +2/+2 until end of turn. Untap it.

Target player draws X cards and loses X life.

Kicker—Return a creature you control to its owner's hand. (You may return a creature you control to its owner's hand in addition to any other costs as you cast this spell.)
Counter target spell. If Shinrei's Ruse was kicked, draw a card.

Engorge (As this enters, mill three cards, then exile a card from among the milled cards.)
Whenever an instant or sorcery card you own is exiled from anywhere, you gain 1 life.

Enchant creature
Enchanted creature gets +3/+2 and attacks each combat if able.

Flying, vigilance
At the beginning of your upkeep, if you have 10 or more life than your starting life total, put a +1/+1 counter on each other creature you control.

Flying
Whenever Skyflock Warrior or another creature you control with flying attacks, create a 1/1 white Bird creature token with flying.

Whenever you make first contact, exile the top card of your library. You gain life equal to its mana value. You may play that card until the end of your next turn. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)

Until your next turn, X target creatures you control gain “Whenever this creature deals combat damage to a player, draw a card” and “{1}: Return this creature to its owner's hand.”

Haste
When Caravan Engulfer enters, creatures you don't control can't block this turn.

Search your library for a cryptic card, reveal it, put it into your hand, then shuffle. (Artifacts, enchantments, and modal spells are cryptic.)

Flash
You may activate Zero's loyalty abilities any time you could cast an instant on your turn and the turn they entered.
[+2]: Destroy up to one target permanent with mana value 4 or greater.
[–2]: You may cast a spell with mana value 5 or less from your hand without paying its mana cost.
[–3]: Look at the top six cards of your library. Put one of them into your hand and the rest on the bottom of your library in a random order.

Trample
Avatar of the Groves enters with a +1/+1 counter on it for each land you control.
Landfall — Whenever a land you control enters, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

Choose two —
• Until end of turn if an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.
• Create three 1/1 green Snake creature tokens.
• Create a 2/2 blue Bird creature token with flying.
• Create a 3/3 red Manticore creature token with haste.

Choose one —
• Create two 1/1 white Soldier creature tokens. They gain haste until end of turn.
• Destroy target nonbasic land.

Create a 2/2 black Zombie creature token.
Tether (Then if you cast this from your hand, you may exile it tethered to a creature you control. When it dies, you may cast this from exile without paying its mana cost.)

Whenever another nontoken creature you control dies, you may return it to the battlefield tapped face down under its owner's control. It's a Forest land.
{4}{G}, Return a land you control to its owner's hand: Create a 3/3 green Wurm creature token. Activate only as a sorcery.