msem-instigator

Whenever Fox of the Mushroom Forest enters or deals combat damage to a player, its activated abilities cost {W} less to activate until your next turn.
{W}, Sacrifice Fox of the Mushroom Forest: Counter target noncreature spell unless its controller pays {2}.

Destroy up to one target artifact or enchantment. Rouse 2. (Distribute two +1/+1 counters among permanents you control. If they aren't creatures, tap them and they become 0/0 creatures in addition to their other types.)

{T}, Sacrifice another permanent: Add one mana of any color.
At the beginning of your end step, if you're horrific, put a +1/+1 counter on target creature. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)

Defender
When Friend of Tides enters, rouse 2. (Distribute two +1/+1 counters among permanents you control. If they aren't creatures, tap them and they become 0/0 creatures in addition to their other types.)

At the beginning of your end step, if you own a card in exile, create a 1/1 white Spirit creature token with flying.

Whenever a creature you control enters for the first time each turn, you may sacrifice it. If you do, exile cards from the top of your library until you exile a creature card. Put that card onto the battlefield.

Put target creature on the bottom of its owner's library. That player reveals cards from the top of their library until they reveal a creature card, then puts all cards revealed this way into their graveyard.

Choose one —
• Creatures your opponents control get -1/-1 until end of turn.
• Harmonize twice. (To harmonize, trigger up to one harmony of a permanent you control.)

Rouse 2, then you gain 1 life for each creature you control. (Distribute two +1/+1 counters among permanents you control. If they aren't creatures, tap them and they become 0/0 creatures in addition to their other types.)

As you harmonize, you may choose another harmony ability to trigger. (They can't be the same harmony.)
Harmony — Scry 1.

Whenever you cast a spell, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Gilded Duo gets +2/+0 until end of turn.

Hexproof
You may have Glen Hunter assign its combat damage as though it weren't blocked.

Archive 3 (As this enters, shuffle the top three 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, put the top card of your main library on the bottom of the archived library.
{W}: Exchange a card from the archived library with a card from your hand.

Spells you cast with mana value 4 or greater cost {1} less to cast.

Exile target creature. Return that creature to the battlefield under its owner's control at the beginning of the next end step.
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.)

For each counter on each permanent you control, you may put another counter of that kind on that permanent.
Draw a card.

When Hail to the Queen enters, each player sacrifices a creature.
Whenever a nontoken creature you control dies, you may pay its mana cost. If you do, create a token that's a copy of it.

Reach
Whenever one or more creatures with flying attack, harmonize. (Trigger up to one harmony of a permanent you control.)
Harmony — Harpstring Ranger gets +2/+2 until end of turn. Untap it.

Menace
At the beginning of your end step, He of All Hallow's Eve deals damage equal to its power to you unless you're horrific. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)

Hellfire Caverns enters tapped.
{T}: Add {R}.
{2}{R}: Until end of turn, Hellfire Caverns becomes a 3/3 Devil creature with menace. Activate only if you're horrific.

Whenever you cast a legendary spell or play a legendary land, put a +1/+1 counter on Henros, Royal Herald and you gain 1 life.
{2}{W}: Look at the top six cards of your library. You may exile a legendary card from among them. Then shuffle. If the exiled card has mana value less than Henros's power, you may put it onto the battlefield tapped. If you don't, put it into your hand.

At the beginning of your upkeep, each opponent mills cards equal to the number of card types among permanents you control.

Reveal the top three cards of your library. Put up to one creature or Revelation card from among them into your hand and the rest into your graveyard.
Coalesce {6}{G} (You may cast this from your graveyard for {6}{G}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
Hold Life in Taloned Grasp's power is equal to the number of cards in your graveyard.

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.)

When Humble Archivist enters, you may return target instant or sorcery card from your graveyard to your hand. If you do, conjure a card named Fatigue and put it on top of your library. (It's a colorless sorcery that costs {2} with “Draw a card.”)