msem-instigator

[+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.”

Trample
Whenever Hellfire Titan enters or attacks, exile the top card of your library and up to one target instant or sorcery card with mana value 3 or less from your graveyard. Until the end of your next turn, you may play those cards.

(Transform this if it's not attached to a creature. Pay {B} as a sorcery to unattach it.)
Enchant creature you control
Herald of Death's rider gets +1/+1.
Sacrifice a creature: Herald of Death's rider gets +2/+2 until end of turn.

(Transform this if it's not attached to a creature. Pay {4}{G} as a sorcery to unattach it.)
Enchant creature you control
Herdstrider's rider gets +1/+1 for each land you control and has trample.
Whenever Herdstrider's rider attacks, create an X/X green Elephant creature token with trample that's tapped and attacking, where X is that creature's power. Exile that token at the end of combat.

When Heretic's Vow enters, create two 1/1 white Cleric creature tokens with lifelink.
Once each turn, when you gain life, you may put a +1/+1 counter on target creature you control.

Prowess
Whenever Hethwyr Warcaster or another Wizard you control enters, you may draw a card.

At the beginning of your upkeep, if you control a legendary creature, you draw a card and you lose 1 life.

Destroy all creatures and planeswalkers with mana value X or less.

Hollowghast, the Iron Phantom enters with three +1/+1 counters on it.
If damage would be dealt to Hollowghast, prevent that damage. Remove a +1/+1 counter from Hollowghast.

Haste
When Horse Thief enters, you may gain control of target creature or Steed until end of turn. It gains haste until end of turn. If it's a Steed, attach it to Horse Thief.

Put a +1/+1 counter on target creature you control. Then that creature fights target creature you don't control. (Each deals damage equal to its power to the other.)

Vigilance
Imisti's Commando can't be blocked by creatures with lesser power.
Whenever Imisti's Commando deals combat damage to a player, draw a card.

Each opponent sacrifices a creature or planeswalker. If you own a foretold card in exile, you gain 4 life.

Whenever Imisti, Elven Insurgent attacks, mill two cards. When you do, you may return target land card from your graveyard to your hand.
{X}{B}{G}: If Imisti has no +1/+1 counters on it, put X +1/+1 counters on Imisti. Activate only as a sorcery.

When Impervious Fortifications enters, you gain life equal to the number of creatures you control.
Creatures can't attack you or a planeswalker you control unless their controller pays {2} for each creature they control that's attacking you.

Enchant creature
You may cast this spell from your graveyard if it targets a legendary creature you control.
Enchanted creature gets +2/+2 and has haste.

{T}: Add {C}.
{5}, {T}: Put a +1/+1 counter on target creature you control. Activate only as a sorcery.

Whenever you cast an instant or sorcery spell, Infernal Immolator deals 2 damage to each opponent.

Improve {W} ({W}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
Whenever one or more embattled creatures you control attack, create a 1/1 white Cleric creature token with lifelink. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Create two 1/1 green Elf creature tokens, then up to one target creature gets +X/+X until end of turn, where X is the number of creatures you control. (Targets are chosen before the tokens are created.)

Whenever a creature you control leaves the battlefield, if it had counters on it, you may put one of those counters on Ironpact Marauder.
{1}{B}, Remove two counters from Ironpact Marauder: You draw a card and you lose 1 life.

Melee (Whenever this creature attacks, it gets +1/+1 until end of turn for each opponent you attacked this combat.)

Whenever you cast a creature or planeswalker spell, if mana produced by a nonland permanent was spent to cast it, it gains trample and haste until end of turn.
{T}: Add {R} or {G}.

{T}: Izahl, the Stormbringer deals 1 damage to any target.
Whenever you cast a noncreature spell, you may untap target creature you control.

Johanna, Skarvith Marshal has first strike as long as it's attacking.
Whenever you attack, you may pay {X}{R/W}{R/W}. When you do, put a +1/+1 counter on each of up to X target attacking creatures. Those creatures gain first strike until end of turn.