Level up (: Put a level counter on this. Level up only as a sorcery.)
LEVEL 2-3
3/3
Flying
LEVEL 4+
4/4
Flying
Other Merfolk creatures you control get +1/+1.

: Add .
: Regenerate target Insect, Rat, Spider, or Squirrel. (The next time it would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Tap an untapped Wizard you control: Counter target spell unless its controller pays .

Vigilance
This creature enters prepared.
Whenever this creature attacks, if you control eight or more lands, this creature becomes prepared.

Whenever Ian the Reckless attacks, if it's modified, you may have it deal damage equal to its power to you and any target. (Equipment, Auras you control, and counters are modifications.)

Whenever you draw your second card each turn, create a 1/1 blue Merfolk creature token.
, : Target Merfolk can't be blocked this turn.

Flying, trample
When Dragonlord Atarka enters, it deals 5 damage divided as you choose among any number of target creatures and/or planeswalkers your opponents control.

Creatures can't attack you unless their controller pays for each creature they control that's attacking you.

You may sacrifice two Mountains rather than pay this spell's mana cost.
Create two 1/1 red Goblin creature tokens.

: Add .

When this creature enters, return target instant or sorcery card from your graveyard to your hand.

Sunburst (This artifact enters with a charge counter on it for each color of mana spent to cast it.)
, Sacrifice this artifact: Destroy each nonland permanent with mana value equal to the number of charge counters on this artifact.

Enchant player
If a card would be put into enchanted player's graveyard from anywhere, instead that card is revealed and put on the bottom of that player's library.

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Choose a nonland card name. Search target player's graveyard, hand, and library for all cards with that name and exile them. Then that player shuffles.

When this creature enters, surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
Whenever one or more other creatures you control enter, if they entered or were cast from a graveyard, create a token that's a copy of one of them. This ability triggers only once each turn.

Whenever an opponent activates an ability of a creature or land that isn't a mana ability, you may draw a card.

Indestructible
As long as your devotion to black and red is less than seven, Mogis isn't a creature.
At the beginning of each opponent's upkeep, Mogis deals 2 damage to that player unless they sacrifice a creature of their choice.

: Add .
: Add . Activate only if you control a Mountain or a Forest.

Other Merfolk get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)