msem-instigator

When Guardian of the Wurm enters the battlefield, create a 6/6 green Wurm creature token with trample.

Enchant creature (Target a creature as you cast this. This card enters the battlefield attached to that creature.)
Enchanted creature gets +2/+1 and has trample.

Target creature gets -3/-3 until end of turn. When that creature dies this turn, its controller loses 2 life.

When Hand of the Evil One enters the battlefield, mill three cards. Draw a card for each Zombie card milled this way.
Unearth abilities you activate cost up to {1} less to activate.

Vanishing 3 (This permanent enters the battlefield with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Hapless Chronomancer dies, if it had no time counters on it, return target instant or sorcery card from your graveyard to your hand.

When Harbinger of Growth enters the battlefield, create a 1/1 green Saproling creature token.
{1}{G}, Sacrifice Harbinger of Growth: Populate. (Create a token that's a copy of a creature token you control.)

Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle. Put a +1/+1 counter on each creature you control.

Whenever you cast an enchantment spell, you may pay {W}. If you do, put a +1/+1 counter on target creature.

Harpoon Launching deals 3 damage to any target. Create a 1/1 red Goblin creature token.

Whenever Harvester of Secrets or another creature enters the battlefield from your graveyard, you may draw a card.
Unearth {2}{U}{B} ({2}{U}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the end step or if it would leave the battlefield. Unearth only as a sorcery.)

When Hate-Driven Arsonist enters the battlefield, you may have it deal X damage to target creature or planeswalker, where X is the number of instant and sorcery cards in your graveyard.

Flying
Whenever Haunter of the Deadlands attacks, Spirit creatures you control get +1/+1 until end of turn.

({T}: Add {U} or {B}.)
Hazy Moorland enters the battlefield tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

({T}: Add {G} or {W}.)
Heart of the Glade enters the battlefield tapped unless you control a basic Forest or a basic Plains.

Menace
Sacrifice a Goblin: Heartless Warleader gets +2/+2 until end of turn.

Kicker {2}{B} (You may pay an additional {2}{B} as you cast this spell.)
Flying
When Heartstabber Mosquito enters the battlefield, if it was kicked, destroy target creature.

Vigilance
{W}: Heaven's Champion gains first strike until end of turn.

Flying, lifelink

Flying (This creature can't be blocked except by creatures with flying or reach.)
Whenever a creature you control with flying attacks, it gets +1/+1 until end of turn.

Flying (This creature can't be blocked except by creatures with flying or reach.)
Heavensent Emissary enters the battlefield with a +1/+1 counter on it for each other creature with flying you control.

Equipped creature has “{T}: Target attacking creature gets +1/+1 until end of turn.”
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Flying
Herald of Oblivion enters the battlefield with X -1/-1 counters on it, where X is your life total.

Flying
Whenever Heroes of Wars Past attacks, attacking Human creatures get +1/+1 and gain flying until end of turn.

Whenever a player cycles a card, that player mills two cards.

When Hollowflesh Ghoul dies, create a 1/1 black Skeleton creature token.