Creatures you control with power greater than their base power can't be blocked by more than one creature.
{G}{W}: Target creature gets +1/+1 until end of turn. Activate only as a sorcery.

Flash
When Benthalos of Land and Sea enters, you may pay {X}. When you do, create a token that's a copy of target white or blue enchantment you control with mana value X or less.

Deathtouch
Whenever a creature you control deals combat damage to an opponent, draw a card. You lose 1 life unless that creature had deathtouch.

When Blackout Grifter enters, each opponent loses 1 life and you gain 1 life.
Cybersoul {3}{B}

Flash
When Blightfang Zyxthax enters, discard a card. If you do, it gains deathtouch until end of turn.

Flash
When Blind Keelah enters and whenever you cast a spell during an opponent's turn, each opponent loses 1 life and you surveil 1. This ability triggers only once each turn.

Flying, haste
When Blistering Cryophoenix enters, discard any number of cards, then draw that many cards.
If a spell you own which had its flashback cost paid would be put into exile, put it into your hand instead.

Lifelink
Approval — {5}, {T}: Tap target creature. This ability costs {X} less to activate, where X is the number of colors among permanents you control.

Haste
Whenever you amp it up, put a +1/+1 counter on Breakbot. It gains first strike until end of turn.

{VP}{VP}{VP}, Sacrifice Bright-Lights Terrier: Creatures you control gain indestructible until end of turn.

Approval — When Cabinet Recruiter enters, you may search your library for a creature card with mana value less than or equal to the number of colors among permanents you control, reveal it, put it into your hand, then shuffle.

When Caller of Ferocity enters, bless target creature.

At the beginning of your upkeep, exile the top card of target opponent's library. You may play that card for as long as it remains exiled, and mana of any type can be spent to cast it.
Spells you cast and don't own cost {1} less to cast.

When Carving Instructor enters, put a flying counter on target creature you control.

Flying, haste
When Chainbreaker's Familiar enters, exile target instant or sorcery card from your graveyard. You may cast a copy of that card until the end of your next turn.
At the beginning of combat on your turn, if you've spent at least five mana to cast spells this turn, you may return Chainbreaker's Familiar from your graveyard to your hand.

{4}{W}, Exile Charging Brightmare from your graveyard: Bless target creature. Activate only as a sorcery.

When Chromatic Hart enters, you may exile target card from a graveyard.
{T}: Add one mana of any color.

Flying
When Civic Copterist enters, teach target creature flying.

Whenever Claes, Shield of Karda attacks, another target attacking creature you control gains indestructible until end of turn.
Whenever a planeswalker you control enters, you may exile Claes, then return him to the battlefield transformed with a number of loyalty counters on him equal to the starting loyalty of that planeswalker.

Haste
{T}: Target creature gains haste until end of turn.
Wander {1}{R}

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

When Codename: Spyder enters, mill three cards.
Whenever one or more cards are put into your graveyard from your library, you may return up to one of those cards to your hand. Do this only once each turn.

When Coercive Contractor enters, create a Treasure token.
{X}, {T}, Sacrifice a Treasure: Gain control of target nontoken creature with mana value X until end of turn. Untap that creature. It gains haste until end of turn. Activate only as a sorcery.

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

You may look at the top card of your library any time.
You may cast artifact and enchantment spells from the top of your library.
{T}, Sacrifice three artifacts and/or enchantments: Search your library for a card, then shuffle and put that card on top.