Each player who doesn't control a planeswalker can't cast more than one spell each turn.
Ayeshicycling {3}

Exile target creature you control, then return that card to the battlefield under its owner's control.

When Perimeter Warden enters, create a 0/3 colorless Wall artifact creature token with defender.
{W}, Sacrifice Perimeter Warden: Target creature you control gains indestructible until end of turn.

Flash
When Permafrost Lynx enters, target creature you don't control doesn't untap during its controller's next untap step.

Defender
{1}{U}: Permafrost Sentry becomes a copy of target Ruin you control.

When Persuasive Orator enters, gain control of target nonland permanent with mana value X until Persuasive Orator leaves the battlefield.

Favored
Your Champion has deathtouch.

Counter target creature spell.
Undercover

Once each turn, when you cast a black spell with mana value less than your devotion to black, you may draw a card and lose 1 life.

Choose one. If your devotion to blue is three or greater, you may choose another. The same is true for devotion to black.
• Target player mills eight cards.
• You gain 1 life for each card type among cards in your opponents' graveyards.
• Draw a card.

Whenever Phenax or another Rogue you control deals damage to a player or planeswalker, each player mills two cards.
{1}{U}{B}, Exile five other cards from your graveyard: Return Phenax from your graveyard to the battlefield transformed. Activate only as a sorcery.

When Photonic Cobra dies, create a 1/1 red and green Elemental creature token.

Return up to one target artifact, enchantment, or land card from your graveyard to your hand.
Create two Berry tokens.

Cast this spell only if an opponent was dealt combat damage this turn.
Draw a card and create a Treasure token.
Maneuver

At the beginning of combat on your turn, if you've cast two or more spells this turn, create an X/X red Shark creature token, where X is the number of spells you've cast this turn. If you've cast six or more spells this turn, Sharks you control gain haste and trample until end of turn.

Whenever a creature attacks you or a planeswalker you control, Pitfall Pangolin gets +1/+0 until end of turn.

Flying
Level up {U/R}
[level 2-4] Flying, prowess
[level 5+] Flying, prowess, prowess, prowess

Each player mills two cards. When you do, return target creature card from your graveyard to your hand.

Put a -1/-1 counter on target creature an opponent controls. Plunder and Maim deals 1 damage to each other creature that opponent controls.

Whenever you cast an enchantment spell, put a +1/+1 counter on Poet of Glory.
Whenever Poet of Glory becomes tapped, return up to one target enchantment card from your graveyard to your hand.

Poised Flame deals 2 damage to any target.
Add {R}{R}. You can't spend this mana to cast spells.

Poisoned Strike deals 3 damage to target creature. That creature's controller mills three cards.

Defender
Approval — Political Prisoner can attack as though it didn't have defender as long as the number of colors among permanents you control is greater than the number of colors among permanents defending player controls.

When Pollen Warning enters, create a 1/1 green Plant creature token, then put a +1/+1 counter on a creature you control.

Pontiff's Page gets +1/+0 and can't be blocked as long as you scried this turn.