, : Target creature gains shroud until end of turn. Activate this ability only during your upkeep. (It can't be the target of spells or abilities.)

Svyelunite Temple enters the battlefield tapped.
: Add .
, Sacrifice Svyelunite Temple: Add .

As an additional cost to cast this spell, tap an untapped creature you control.
Exile target tapped creature. Put a +1/+1 counter on the creature tapped to pay this spell's additional cost.

Each player exiles a creature they control. Until the Hydra's next turn, when a Head leaves the battlefield, return the exiled cards to the battlefield under their owners' control.

Counter target enchantment, instant, or sorcery spell. Its controller creates a 2/2 blue Bird creature token with flying.

Flying
If a source would deal damage to Swans of Bryn Argoll, prevent that damage. The source's controller draws cards equal to the damage prevented this way.

Whenever you cast an instant or sorcery spell, you may copy that spell. You may choose new targets for the copy.

: Add .
: Regenerate target Insect, Rat, Spider, or Squirrel.

Any number of target creatures become the color of your choice until end of turn.
Draw a card.

Each player shuffles their hand, graveyard, and all permanents they own into their library, then draws seven cards. Each player's life total becomes 7.

Return target creature to its owner's hand. If that creature is attacking, you may put it on top of its owner's library instead.

Target player mills four cards.
Escape—, Exile four other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)

Creatures you control get +2/+2 until end of turn.
Reinforce X— (, Discard this card: Put X +1/+1 counters on target creature.)

Until end of turn, target creature gets +1/+0 and gains first strike and lifelink.

Prevent the next 2 damage that would be dealt to any target this turn.
Draw a card at the beginning of the next turn's upkeep.

Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, you may cast Swift Reckoning as though it had flash. (You may cast it any time you could cast an instant.)
Destroy target tapped creature.

Destroy target tapped creature.

Counter all other spells. Draw a card for each spell countered this way.

Equipped creature has hexproof and haste.
Equip

Swimmer in Nightmares gets +3/+0 as long as there are ten or more cards in a single graveyard.
Swimmer in Nightmares can't be blocked as long as you control an Ashiok planeswalker.