msem-instigator

Flying
When Horned Spy enters, look at target player's hand.

No more than two creatures can attack each combat.

You may put a permanent card from your hand onto the battlefield.
Rerun (If you cast this from your hand, exile it as it resolves. Whenever a creature you control dies, you may cast this card from exile without paying its mana cost.)

Trample
Whenever Horrific Progenitor deals damage to a player, for each damage dealt, that player loses 3 life unless they sacrifice a nonland permanent or discard a card.

Return up to one target permanent card and up to one target Horror card from your graveyard to your hand.

Pressure {3}{B} (You may cast this spell for its pressure cost if seven or more cards are in your graveyard.)
Return target creature card from your graveyard to your hand. If this spell was cast for its pressure cost, put that card onto the battlefield instead.

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.

Whenever this creature enters or attacks, create a 2/1 white Soldier creature token. Exile up to one target nonland permanent with mana value 3 or less an opponent controls until that token leaves the battlefield.
Other permanents you control have ward {1}.

Whenever this creature enters or attacks, each player discards a card. If one or more land cards were discarded this way, this creature gains deathtouch until end of turn.
At the beginning of each opponent's end step, if that player didn't cast a spell this turn, that player loses 2 life and you gain 2 life.

Whenever this creature enters or attacks, put two -1/-1 counters on up to one target creature with power less than this creature's power.
Whenever another creature dies, you gain 2 life. If you controlled that creature, draw a card.

Whenever this creature enters or attacks, you may put a creature card with mana value 2 or less from your hand onto the battlefield. If you do, draw a card. Sacrifice that creature at the beginning of the next end step.
If a creature would enter under your control during combat on your turn, that creature enters tapped and attacking.

Flying, lifelink

When Host of Nature enters, create two 2/2 red and green Elk creature tokens.

Whenever you cast a noncreature spell, any number of target creatures you control get +1/+1 until end of turn.
Whenever a creature you control deals an amount of combat damage exactly equal to its mana value to a player or planeswalker, draw a card.

Tap an untapped Desert you control: Hostile Atmosphere deals 1 damage to any target.

Flying
When Hostile Barbfly enters, you may have it consume. When you do, target creature gets -2/-2 until end of turn. (To consume, sacrifice another creature or exile a creature card from your graveyard.)

Hostile Habitat deals 2 damage to each creature.
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.)

Alpha (You may have this creature enter with a +1/+1 counter on it. If you do, it becomes alpha and can only attack alone.)
Lifelink

Flash
When Hostile Takeover enters, you may counter target noncreature spell.
At the beginning of your upkeep, you may put a progress counter on a Project you control.

Up to one target creature gains flying until end of turn. (Then exile this card. You may cast the creature later from exile.)

This spell costs {3} less to cast if a permanent you controlled advanced this turn.
Gain control of target creature until end of turn. Untap it. It gains haste until end of turn.

Target creature you control gets +2/+0 until end of turn. If that creature is attacking, you may aetherize it. (To aetherize, create a token that's a copy of it, then exile that token.)

This spell costs {1} less to cast for each creature that attacked this turn.
Hot to the Touch deals X damage to any target.

{T}: Hotblooded Sorcerer deals 1 damage to target player or planeswalker.
Attain {3}{R} ({3}{R}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

Whenever you make first contact, Hotshot Renegade deals 2 damage to up to one target creature or planeswalker. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)