msem-instigator

When Azutahn Hydromancer enters, you may return target creature with power X or less to its owner's hand, where X is the number of differently named lands you control.

Whenever Babbling Experiment or another creature you control enters, target player mills two cards.

Put two +1/+1 counters on target creature. Untap that creature.

Destroy target creature. Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

[+1]: Exile up to two target cards from graveyards. You gain 3 life.
[–2]: Exile target artifact, enchantment, or nonbasic land.
[–7]: You get an emblem with “At the beginning of your upkeep, exile target noncreature permanent.”

When Bal's Descent enters, each player sacrifices a creature, discards two cards, and mills three cards.
{1}{B}{B}: Transform Bal's Descent. Activate only if your fealty to Swamps is five or greater.

Whenever Baljurn, the Runelord or another nontoken artifact or enchantment you control enters, create a 0/0 blue Construct artifact creature token. Put a +1/+1 counter on each artifact and/or enchantment creature you control other than Baljurn.

Equipped creature gets +3/+0 and has vigilance.
Equip {3}

Destroy target face-up creature.

Engorge (As this enters, mill three cards, then exile a card from among the milled cards.)
When Bane of Sanity enters, if it engorged a creature card, target player discards two cards.

When Baneblade Stalker enters, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

Gain control of target artifact or creature until end of turn. Untap it. If it's a creature, it gains haste until end of turn and up to one target creature can't block it this turn.

Trample
When Bank Skimmer enters, create a green Aura enchantment token named Turtle's Valor attached to target creature. The token has enchant creature and “Enchanted creature gets +X/+X, where X is its mana value.”

Choose two —
• Target player creates two 2/2 white Knight creature tokens with vigilance.
• Destroy target creature with power 4 or greater.
• Target player gains hexproof until end of turn.
• Return target nonland permanent you don't control to its owner's hand.

Other Warriors you control have first strike.
Other Barbarians you control get +1/+0.

Deathtouch
Whenever a creature dealt damage by Barbed Beast this turn dies, transform Barbed Beast.

Wither (This deals damage to creatures in the form of -1/-1 counters.)
Whenever Barrow Banshee deals combat damage to an opponent, that player discards a card at random.

Vigilance
Whenever Bartimus attacks, another target attacking creature gets +1/+1 until end of turn. If that creature is a Soldier, put a +1/+1 counter on it instead.

Menace
Cat creatures you control have menace.
When Basat Priest enters, create a 2/2 white Cat creature token.

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
{1}{G}: Bastion Ranger gains reach and deathtouch until end of turn.

Flying, first strike, vigilance, lifelink
When Bastion Valkyrie dies, create three Function tokens with “Choose a creature targeted by this spell. It gains flying, first strike, vigilance, and lifelink until end of turn.” (They're enchantments. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

Creatures you control have “{T}: Add {C}.”
Mirage {1}{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 Batiga Escort enters, create a 1/1 blue Bird creature token with flying.
{2}{W}, {T}: Put a +1/+1 counter on each creature you control with flying.

Creatures you control get +2/+1 until end of turn. Scry 1.