Whenever you attack, put a +1/+1 counter on a creature you control.

Flying
Whenever Cloud Coatl attacks, target player mills two cards.
Reflect {3}{G}

Attacking creatures get +1/+1 until end of turn. If an attacking creature has vigilance, untap all attacking creatures. Then if an attacking creature has flying, all attacking creatures gain flying until end of turn. The same is true for first strike, double strike, deathtouch, hexproof, indestructible, lifelink, menace, and trample.

When Codename: Ant dies, you may search your library for a card named Codename: Ant, reveal it, put it into your hand, then shuffle.

Whenever Cold Blood attacks, create a first strike Gadget, then attach it to another target attacking creature.
Whenever an enchanted or equipped creature you control becomes the target of a spell or ability an opponent controls, that creature deals damage equal to its power to that player.

Vigilance
Whenever a Subroutine you control runs, this creature gets +1/+0 until end of turn and can't be blocked this turn.

{T}, Sacrifice an artifact: Add one mana of any type.
Once each turn, when you cast an instant or sorcery spell, you may create a 1/1 colorless Construct artifact creature token.

Enchant creature
When Collector's Item enters, surveil 2.
Enchanted creature loses all abilities and is a colorless Sculpture creature with base power and toughness 0/2.

Vigilance
{T}, Sacrifice a creature: Target creature can't be blocked this turn. Activate only if you control a black permanent.

Unite with one or more creatures
When Combat-Form Instructor unites creatures, put a +1/+1 counter on each creature it united.

Create a 0/0 white Army creature token if your devotion to white is three or more.
Put a +1/+1 counter on each creature you control.

Surveil 1. When you do, return target card from your graveyard to your hand. Exile Commune with the Veil.

Equipped creature gets +1/+1 and has “Whenever this creature attacks, surveil 1.”
Equip {1}

Corrupt — When this creature enters, if it isn't a token and you control a permanent with greater mana value than it, create a token that's a copy of this creature.
{T}: Add {G}.

Endgame
{T}: Target player mills a card. If you're in your endgame, that player mills two cards instead.

Gain control of up to two target creatures with total mana value 4 or less until end of turn. Untap one of them. It gains haste until end of turn.

{T}: Draw a card, then discard a card. Activate this ability only if you've disturbed the peace this turn.

Counter target activated ability from a nonland source.
Draw a card.

Enchant creature
Enchanted creature gets +1/+1 and has “Whenever this creature deals combat damage to a player, draw a card.”
{VP}{VP}{VP}: Enchanted creature gains flying until end of turn.

When Contest Coordinator enters, look at the top five cards of your library. You may reveal a Plains card or a nonland card with an activated ability from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Once each turn, when you activate a nonmana ability, you gain 2 life.

When Convoy Forerunner dies, choose one —
• Create a 1/1 white Nomad creature token with vigilance.
• Search your library for a Nomad card, reveal it, then shuffle and put that card on top of it.

Corgan Bourgeois's power is equal to the number of artifacts you control.
Whenever Corgan Bourgeois or another artifact you control enters, you gain 1 life.

Whenever a creature dies, scry 1.

Whenever a creature you control deals combat damage to a player, you may sacrifice it. If you do, draw a card. Otherwise, surveil 1.