You have hexproof. (You can't be the target of spells or abilities your opponents control.) If a creature would deal damage to you, prevent 1 of that damage.

Flying, vigilance {T}: When target creature other than Adarkar Valkyrie dies this turn, return that card to the battlefield under your control.

{W}{U}, {T}: Put a bribery counter on target creature you don't control. Its controller draws a card. Creatures with bribery counters on them can't attack or block.

{W}, {T}: Harpoon Sniper deals X damage to target attacking or blocking creature, where X is the number of Merfolk you control.

Flying, protection from all colors

Other Merfolk creatures you control get +1/+1. Whenever you cast a Merfolk spell, you may tap or untap target permanent.

{T}: Target creature gets -X/-0 until end of turn, where X is the number of Merfolk and/or Faeries you control.

Islandwalk (This creature can't be blocked as long as defending player controls an Island.) {1}{W}: Target Merfolk you control gains protection from the color of your choice until end of turn.

Flying {X}: Prevent the next X damage that would be dealt to you this turn. If damage is prevented this way, Vengeful Archon deals that much damage to target player or planeswalker.

Whenever you draw a card, put a +1/+1 counter on each other Merfolk and/or Knight you control.

When Detention Sphere enters the battlefield, you may exile target nonland permanent not named Detention Sphere and all other permanents with the same name as that permanent. When Detention Sphere leaves the battlefield, return the exiled cards to the battlefield under their owner's control.

At the beginning of each opponent's end step, if you didn't lose life this turn, you may put a quest counter on Luminarch Ascension. (Damage causes loss of life.) {1}{W}: Create a 4/4 white Angel creature token with flying. Activate only if Luminarch Ascension has four or more quest counters on it.

Azorius Chancery enters the battlefield tapped. When Azorius Chancery enters the battlefield, return a land you control to its owner's hand. {T}: Add {W}{U}.

({T}: Add {U}.)

({T}: Add {W}.)

Sejiri Refuge enters the battlefield tapped. When Sejiri Refuge enters the battlefield, you gain 1 life. {T}: Add {W} or {U}.