msem-instigator

The Last Sacred Gate enters tapped.
While you're searching your library, you may play The Last Sacred Gate from your library. (You may only do so during your turn and if you have a land play remaining.)
{T}: Add {C}.

Head on Collision deals 2 damage to any target.
Leitmotif (If you cast this spell from your hand, exile it as it resolves. When you next cast a spell that shares a color with this card, you may cast this from exile without paying its mana cost.)

Haunted Hovel enters tapped.
{T}: Add {W} or {B}.
When Haunted Hovel enters, you may put a loyalty counter on a planeswalker you control.

[+1]: Distribute two +1/+1 counters among any number of target creatures you control.
[–1]: Create two 1/1 white Monk creature tokens.
[–6]: Until your next turn, you choose which creatures attack or block and how those creatures attack or block.

Equipped creature gets +2/+0 and can't be blocked.
Whenever a Rogue you control attacks, you may pay {1}. If you do, attach Saber of Defiled Rites to it.
Equip {5}

Flash
Harmony — Another target creature gets +1/+0 and gains indestructible until end of turn.
When Siamang Tale-Singer enters, harmonize. (Trigger up to one harmony of a permanent you control.)

Scoured Mesa enters tapped.
{T}: Add {W}.
Desertcycling {1}{W} ({1}{W}, Discard this card: Search your library for a Desert card, reveal it, and put it into your hand, then shuffle.)

Put target creature on top of its owner's library. You create a token that's a copy of that creature.

[+2]: Target player exiles a card from their hand at random. Until the end of that player's next turn, they may play that card.
[0]: Gain control of target creature or planeswalker until end of turn. Tap it.
[–9]: Take an extra turn after this one. During that turn, you control all opponents.

Menace
Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
Gilded Sell-Sword gets +2/+0 as long as you're in a renaissance.

Reach
Erratic (When this creature dies, reveal the top four cards of your library. Put a creature card that costs less than this revealed this way onto the battlefield and the rest on the bottom of your library in any order.)

Flash
Motivate 7 (When this creature enters, you may motivate target creature with less power than this by putting seven +1/+1 counters on it.)

First strike
When Imperial Dragoon enters, target creature gets +2/+0 until end of turn.

Destroy all creatures. Amass Soldiers X, where X is the number of creatures destroyed this way. (Put X +1/+1 counters on an Army you control. It's also a Soldier. If you don't control one, create a 0/0 black Soldier Army creature token first.)

Enchant creature you control
Enchanted creature has lifelink.
When Phantasmal Possession enters, exile target creature an opponent controls until Phantasmal Possession leaves the battlefield.

When Blinding Fiddler enters, until your next turn, creatures can't attack you or a planeswalker you control unless their controller pays {2} for each of those creatures.
Unveil {3}{W}{U} ({3}{W}{U}: Transform this. Unveil only as a sorcery.)

{U}, Give yourself a lore counter: Scry 1. This ability costs {2} more to activate for each lore counter you have.
{6}{U}, Remove three lore counters from yourself, Sacrifice Harbinger of Giradrus: Draw seven cards, then create two 4/4 red Dragon creature tokens with flying.

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.)

When Bug Catcher enters, create a 1/1 green Insect creature token.
Whenever a nontoken Insect you control dies, create a 1/1 green Insect creature token.

If a creature entering the battlefield under your control causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
{1}{U}, {T}: Exile another target creature. Return it to the battlefield under its owner's control at the beginning of the next end step.

Destroy target non-Gorgon creature. Scry 1.

{2}{R}: Thespian Soldier gains first strike until end of turn.

{4}{G}, Sacrifice Elvish Godtracker: Create a 5/5 green Beast creature token.

Flying
Sire of Empires gets +1/+1 as long as you control another creature, has lifelink as long as you control an enchantment, and has vigilance as long as you control an artifact.

Enchant creature
When Bloodbriar Blessing enters, draw a card.
Enchanted creature gets +2/+2 and has menace.