Atraxa, Praetors' Voice

Flying, vigilance, deathtouch, lifelink
At the beginning of your end step, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Lighthouse Chronologist

Level up {U} ({U}: Put a level counter on this. Level up only as a sorcery.)
LEVEL 4-6
2/4
LEVEL 7+
3/5
At the beginning of each end step, if it's not your turn, take an extra turn after this one.

Vorel of the Hull Clade

{G}{U}, {T}: Double the number of each kind of counter on target artifact, creature, or land.

Deepglow Skate

When Deepglow Skate enters, double the number of each kind of counter on any number of target permanents.

Luminarch Ascension

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.

Gilder Bairn

{2}{G/U}, {Q}: Double the number of each kind of counter on target permanent. ({Q} is the untap symbol.)