msem-instigator

Flash
You may cast Elemental spells as though they had flash.
Once each turn, when you cast an instant spell, you may put a +1/+1 counter on target Elemental you control.

Converge — You draw X cards and gain X life, where X is the number of colors of mana spent to cast Animus Vox.

Flying, vigilance
Augmented — When Antigravity Agent enters the battlefield, if you've spent {W}{U}{R}{B}{G} to cast spells this turn, distribute a flying counter and a vigilance counter among one or two creatures you control.

This spell costs {1} less to cast for each storied permanent you control. (Enchantments and legendary permanents are storied.)
Counter target spell.
Draw a card.

Vigilance, trample
Whenever another Horror enters the battlefield under your control, choose one —
• Destroy target artifact or enchantment.
• You gain 4 life.
• Apex Abomination fights another target creature.

At the beginning of your upkeep, if an opponent controls more creatures than you, you may reveal the top seven cards of your library. Target opponent chooses a creature card revealed this way. Put that card onto the battlefield, and the rest into your graveyard.

At the beginning of your upkeep, if you control ten or more storied permanents, you win the game. (Enchantments and legendary permanents are storied.)

Other creatures you control can't attack or block alone.

Flash
Flying
As long as an opponent controls more creatures than you, Arbiter of the Scales gets +2/+2 and has first strike and lifelink.

Activated abilities of artifacts cost {2} more to activate.

Whenever Arcane Metalcrafter or another Wizard you control attacks, create a 1/1 colorless Construct artifact creature token that's tapped and attacking.
Whenever a Construct you control dies, Arcane Metalcrafter deals 1 damage to each opponent.

Whenever you cast a noncreature spell, Architect of Calamity deals 2 damage to each opponent.

When Architect of the Derezzed enters the battlefield, create two 1/1 colorless Servo artifact creature tokens.
Sacrifice an artifact: Target creature can't be blocked this turn.

Whenever you cast a noncreature spell, each opponent loses 1 life.
{4}, Exile Arisen Psion from your graveyard: Draw a card.

Trample
Arpechian Champion can only attack or block alone.
Whenever a land enters the battlefield under your control, put a +1/+1 counter on Arpechian Champion.

Create a 1/1 colorless Construct artifact creature token. If you control six or more artifacts, create a 6/6 colorless Golem artifact creature token instead.
Draw a card.

Sabotage — Whenever an opponent or permanent an opponent controls becomes the target of a spell you control, Artisan of Brutality gets +2/+0 and gains first strike until end of turn.

When Artisan's Genius enters the battlefield, you may tap three untapped artifacts or other enchantments you control. If you do, draw three cards.
{5}{W}{U}, Exile Artisan's Genius: Return any number of artifact or enchantment cards with different names from your graveyard to your hand.

When Artistic Vision enters the battlefield, create two 1/1 colorless Construct artifact creature tokens.
Whenever you cast an instant or sorcery spell, you may tap two untapped artifacts you control. If you do, copy that spell. You may choose new targets for the copies.

Augmented — When you cast this spell, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, copy it twice.
Choose a nonland permanent type. Each player sacrifices a permanent of the chosen type.

Flying
When Ascended Explorer enters the battlefield, return target creature card with mana value 2 or less from your graveyard to the battlefield.

Rhapsody {3}{W}{W} (Pay {3}{W}{W} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Lifelink

Whenever a nonbasic land becomes tapped or enters the battlefield tapped, it doesn't untap during its controller's untap steps for as long as Ataraxia remains on the battlefield.

When Atrocity of Flesh enters the battlefield, destroy target nonland permanent.
When Atrocity of Flesh dies, you may exile it. If you do, return target card from your graveyard to your hand.

Haste
Augmented — When Attuned Lifeform enters the battlefield, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, put a +1/+1 counter on each creature you control. They gain vigilance until end of turn.