Enchant creature
Enchanted creature gets +2/+2.

Haste
Echo (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When this creature enters, destroy target land.

Destroy target artifact or enchantment, then populate. (Create a token that's a copy of a creature token you control.)

Whenever a creature you control attacks alone, it gets +X/+X until end of turn, where X is the number of creatures you control.
, Discard this card: It deals damage equal to the number of creatures you control to target creature.

Enchant creature
Enchanted creature gets +1/+1 and has vigilance.
When enchanted creature dies, manifest the top card of your library. (Put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)

When this creature enters, open an Attraction. (Put the top card of your Attraction deck onto the battlefield.)

Menace (This creature can't be blocked except by two or more creatures.)
, Sacrifice another creature or an artifact: This creature deals 2 damage to target creature or planeswalker.

Exile target creature with power 4 or greater.

Counter target spell unless its controller pays .

Counter target spell with mana value 1 or less.

: Target player loses 1 life.

Green creatures you control have trample.

Creatures with power less than this creature's power can't block it.

If you control a Forest, rather than pay this spell's mana cost, you may have an opponent gain 3 life.
Target creature gets +4/+4 until end of turn.

Ward (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays .)
Enlist (As this creature attacks, you may tap a nonattacking creature you control without summoning sickness. When you do, add its power to this creature's until end of turn.)

Flying
When this creature enters, you get six (energy counters).
Pay : Return this creature to its owner's hand.

, Discard a card: Create a 0/3 blue Crab creature token.
Delirium — Crabs you control get +1/+1 as long as there are four or more card types among cards in your graveyard.

Escalate—Discard a card. (Pay this cost for each mode chosen beyond the first.)
Choose one or more —
• Target opponent reveals their hand. You choose an instant or sorcery card from it. That player discards that card.
• Target creature gets -2/-2 until end of turn.
• Target opponent loses 2 life and you gain 2 life.

Haste
Whenever a creature an opponent controls dies, put a +1/+1 counter on Yahenni.
Sacrifice another creature: Yahenni gains indestructible until end of turn.

When this creature dies, create a Treasure token. (It's an artifact with ", Sacrifice this token: Add one mana of any color.")
Encore (, Exile this card from your graveyard: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)