msem-instigator

{W}{B}{G}, Discard a card named Bahet, God of Destruction: Bahet gains indestructible and becomes a God creature in addition to its other types.
Whenever Bahet enters or attacks, each player chooses a number of lands they control equal to the number of lands controlled by the player who controls the fewest, then sacrifices the rest. Players discard cards and sacrifice non-God creatures the same way.

When Makshi, Patron of Blades enters, search your library for an Equipment card, reveal it, put it into your hand, then shuffle. Add {W}{U}{B}{R}{G}. Spend this mana only to cast Equipment spells and activate abilities of Equipment.

Choose four nonland card names. Target opponent reveals their hand and discards all cards with the chosen names.

When Mirror Paradigm enters, conjure a card named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)
Once each turn, when a sorcery card is put into your graveyard from anywhere, you may copy it. If you do, you may cast the copy. (You still pay its costs.)

{T}: Add {C}.

Reach
Whenever one or more creatures with flying attack, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Harpstring Ranger gets +2/+2 until end of turn. Untap it.

[+1]: Up to two target creatures you control each get +1/+1 and gain vigilance until end of turn.
[–3]: Create two 1/1 white Dwarf Peasant creature tokens. You gain 2 life.
[–7]: You get an emblem with “Creatures you control get +2/+2 and have double strike.”

Whenever a source you control deals damage to an opponent this turn, exile the top card of your library. You may play it this turn.

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Flying
Dragon spells you cast have cascade.

Vanishing 5 (This creature enters with five time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
{1}{R}, Remove a time counter from Unstable Magmaling: Flip a coin. If you win the flip, it deals 3 damage to any target.

Put a +1/+1 counter on target creature you control. It can't be blocked this turn.
Flashback {3}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Sacrifice Chromeleon: Add one mana of any color. Scry 1.

Enchant creature
Whenever enchanted creature attacks, audition for green. (Create a 1/1 Construct Actor creature token, a Scout Role giving 2/3 and vigilance, or a Warrior Role giving 3/2 and trample. Roles replace older ones.)

Menace
Pay 2 life: Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
Sacrifice a permanent: Darna gets +1/+1 until end of turn.

At the beginning of combat on your turn, choose a permanent type at random. Each player sacrifices a permanent of the chosen type other than this enchantment. If no permanents were sacrificed this way, sacrifice this enchantment and create a 6/6 black and red Rat Mutant creature token with trample and haste.

Enchant artifact or creature
Enchanted permanent can't attack and its activated abilities can't be activated.

Wanderlust — When Ardent Explorers enters, if you control four or more differently named lands, create a 1/1 Scout creature token that's all colors. That token gains haste until end of turn.

Archive 7 (As this enters, shuffle the top seven cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
As long as you control five or more creatures, you may play permanent cards from the archived library.

Vigilance

Exile target permanent. Smite the Unruly deals damage equal to that permanent's mana value to its controller and you gain that much life.

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.

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
Whenever a Demon you control enters, put a +1/+1 counter on Tzelin.
{2}{B}: Sacrifice Tzelin. If you do, each opponent loses life equal to Tzelin's power. If you're in a renaissance, also draw that many cards.

As Toxic Spring enters, you may tap an untapped creature you control. If you don't, Toxic Spring enters tapped.
{T}: Add {U} or {B}.

Flash
Flying
Whenever H13 Wasp enters or you cast an another spell with flash or an instant, exile up to one target nonland permanent. Return that card to the battlefield under its owner's control at the beginning of the next end step.

This spell has flash as long as an opponent is cursed.
Return target creature to its owner's hand.
Draw a card.