msem-instigator

Double strike
Whenever an Equipment enters the battlefield under your control, create a 3/3 white Archon creature token with flying and attach that Equipment to that token.

(As this Discovery enters and after your draw step, add a progress counter. Stop after you've discovered.)
I, II — Each opponent loses 2 life and you gain 2 life.
Discovery — At the beginning of your end step, you draw a card and you lose 2 life.

Flying, vigilance
When Tyriel, Angelic Artisan enters the battlefield, you may search your library for an Equipment card, reveal it, put it into your hand, then shuffle.
Whenever Tyriel attacks, you may put an Equipment card from your hand onto the battlefield, then attach it to Tyriel.

Flash
When Tyrus, Giver to All enters the battlefield and at the beginning of combat on your turn, for each counter on permanents you control, you may move that counter from that permanent to another permanent you control.

Tzelin of the Demon Realm can't block.
Whenever a Demon enters the battlefield under your control, you may pay {B}. If you do, return Tzelin from your graveyard to the battlefield with a +1/+1 counter on it.

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 enters the battlefield under your control, 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.

You may play cards exiled with Azamir planeswalkers.
[+1]: Target player exiles a card from their hand.
[–3]: Exile target nonland permanent unless its controller exiles two other permanents they control.
[–7]: Target opponent may have you take two extra turns after this one. If they don't, you control them during their next turn.

Archive 4 (As this enters the battlefield, shuffle the top four cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
Whenever you draw a card from the archived library, destroy all nonland permanents you don't control with the same mana value as the drawn card.

Equipped creature gets +2/+2.
Whenever equipped creature attacks, creature spells you cast cost {2} less to cast this turn.
Equip {2}

Whenever Ujuraq, Elder Watcher enters the battlefield or attacks, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)
Ujuraq gets +3/+3 and has trample as long as there are eight or more cards in your graveyard.

Other Hounds you control have trample.
{R/W}, {T}: Put a +1/+1 counter on target Hound you control.

Enchant creature
Enchanted creature can't be blocked.
{1}{G}: Enchanted creature gets +1/+1 and gains hexproof until end of turn.

When Unbound Expanse enters the battlefield, if an opponent controls more lands than you, create a Plains token. (It's a basic land with “{T}: Add {W}.”)
{1}{W}, Sacrifice Unbound Expanse: Exile each nonland permanent you control, then return those cards to the battlefield under your control.

Whenever a creature you control is dealt damage, put a +1/+1 counter on that creature.

Enspirit (As you cast this spell, you may exile a nonenchantment creature you control until this leaves the battlefield or fails to resolve. Reduce this spell's cost by the exiled card's mana value.)
Deathtouch

When Uncovered Mine enters the battlefield and at the beginning of your upkeep, return a random card from your graveyard to your hand.

When Uncovered Secrets enters the battlefield, search your library for an artifact card, reveal that card, then shuffle and put that card on top.
Concord — Creatures you control get +1/+1 as long as there are four or more card types among permanents you control.

Creature cards in your graveyard have revive {2}{B}{B}. ({2}{B}{B}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Enchant creature
Enchanted creature gets +1/+0 and has menace. (That creature can't be blocked except by two or more creatures.)

Enchant land you control
Whenever enchanted land is tapped for mana, it produces an additional mana of that type.
{1}{G}, Sacrifice Under Untamed Skies: Destroy target creature with flying.

At the beginning of each opponent's upkeep, that player may discard their hand. If the player does, sacrifice Under the Gun. Otherwise, put a bullet counter on Under the Gun, then that player loses life equal to the number of bullet counters on it.

Concord — As long as there are four or more card types among permanents you control, you may cast the first spell you cast each turn without paying its mana cost.

This spell costs {1} less to cast for each artifact you control. (This applies before Treasures are sacrificed for mana.)
When Underhanded Deal enters the battlefield, draw three cards.
Whenever you cast a spell, you lose 1 life.

When Undermarket Favors enters the battlefield, target player discards a card, then mills four cards.
{1}, Sacrifice Undermarket Favors: Draw a card.

Bleed {1}{B} (You may cast this spell for its bleed cost if an opponent lost life this turn.)
When Undermurk Scavenger enters the battlefield, you draw a card and you lose 1 life.