Deal combat damage twice

• Kutzil, Malamet ExemplarWhenever one or more creatures you control each with power greater than its base power deals combat damage to a player, draw a card.
• Toski, Bearer of SecretsWhenever a creature you control deals combat damage to a player, draw a card.
• Ohran FrostfangWhenever a creature you control deals combat damage to a player, draw a card.

Then: Put a +1/+1 counter, Put a counter, Create a token

• Nashi, Moon Sage's ScionWhenever ~ deals combat damage to a player, exile the top card of each player's library. until end of turn, you may play one of those cards. if you cast a spell this way, pay life equal to its mana value rather than paying its mana cost.
• Ragavan, Nimble PilfererWhenever ~ deals combat damage to a player, create a treasure token and exile the top card of that player's library. until end of turn, you may cast that card.
• Tinybones, the PickpocketWhenever ~ deals combat damage to a player, you may cast target nonland permanent card from that player's graveyard, and mana of any type can be spent to cast that spell.

Then: Copy a spell or ability, Put a counter, Put a +1/+1 counter

• Ragavan, Nimble PilfererWhenever ~ deals combat damage to a player, create a treasure token and exile the top card of that player's library. until end of turn, you may cast that card.
• Ancient Copper DragonWhenever this creature deals combat damage to a player, roll a d20. you create a number of treasure tokens equal to the result.
• Professional Face-BreakerWhenever one or more creatures you control deal combat damage to a player, create a treasure token.

Then: Leave the battlefield, Sacrifice a permanent, Become tapped

• Mask of MemoryWhenever equipped creature deals combat damage to a player, you may draw two cards. if you do, discard a card.
• Stinkweed ImpWhenever this creature deals combat damage to a creature, destroy that creature.
• Scion of CalamityWhenever this creature deals combat damage to a player, destroy target artifact or enchantment that player controls.

Then: Leave the battlefield, Return a card from a graveyard, A creature enters the battlefield

• Giant AdephageWhenever this creature deals combat damage to a player, create a token that's a copy of this creature.
• Ragavan, Nimble PilfererWhenever ~ deals combat damage to a player, create a treasure token and exile the top card of that player's library. until end of turn, you may cast that card.
• Professional Face-BreakerWhenever one or more creatures you control deal combat damage to a player, create a treasure token.

Then: Enter the battlefield, A creature enters the battlefield, permanents to sacrifice

• Port RazerWhenever this creature deals combat damage to a player, untap each creature you control. after this phase, there is an additional combat phase.
• BloodthirsterWhenever this creature deals combat damage to a player, untap it. after this phase, there is an additional combat phase.
• Marisi, Breaker of the CoilWhenever a creature you control deals combat damage to a player, goad each creature that player controls.

Then: Deal combat damage, Deal combat damage twice, Put a +1/+1 counter

• ThrummingbirdWhenever this creature deals combat damage to a player, proliferate.
• Grateful ApparitionWhenever this creature deals combat damage to a player or planeswalker, proliferate.
• Bloated ContaminatorWhenever this creature deals combat damage to a player, proliferate.

Then: Become tapped, A creature enters the battlefield, Create a token

• Ancient Silver DragonWhenever this creature deals combat damage to a player, roll a d20. draw cards equal to the result. you have no maximum hand size for the rest of the game.
• Ancient Brass DragonWhenever this creature deals combat damage to a player, roll a d20. when you do, put any number of target creature cards with total mana value x or less from graveyards onto the battlefield under your control, where x is the result.
• Ancient Gold DragonWhenever this creature deals combat damage to a player, roll a d20. you create a number of 1/1 blue faerie dragon creature tokens with flying equal to the result.

Then: Put a counter, Put a +1/+1 counter, Create a token

• ThrummingbirdWhenever this creature deals combat damage to a player, proliferate.
• Grateful ApparitionWhenever this creature deals combat damage to a player or planeswalker, proliferate.
• Bloated ContaminatorWhenever this creature deals combat damage to a player, proliferate.

Then: Create a token, A creature enters the battlefield, Put a card from your library into a graveyard

• Aurora ShifterWhenever this creature deals combat damage to a player, you get that many {E}.
• Pia Nalaar, Chief MechanicWhenever one or more artifact creatures you control deal combat damage to a player, you get {E}{E} .
• Overclocked ElectromancerWhenever this creature deals combat damage to a creature, if that creature was dealt excess damage this turn, you get x {E}, where x is that excess damage.

Then: An artifact enters the battlefield, Become tapped, Put a +1/+1 counter

• Drana, Liberator of MalakirWhenever ~ deals combat damage to a player, put a +1/+1 counter on each attacking creature you control.
• Sphere GridWhenever a creature you control deals combat damage to a player, put a +1/+1 counter on that creature.
• Scurry of SquirrelsWhenever this creature deals combat damage to a player, put a +1/+1 counter on target creature you control.

• Ragavan, Nimble PilfererWhenever ~ deals combat damage to a player, create a treasure token and exile the top card of that player's library. until end of turn, you may cast that card.
• Kodama of the West TreeWhenever a modified creature you control deals combat damage to a player, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
• Professional Face-BreakerWhenever one or more creatures you control deal combat damage to a player, create a treasure token.

Then: Create a token, Put a counter, Put a +1/+1 counter

• Duelist's HeritageWhenever one or more creatures attack, you may have target attacking creature gain double strike until end of turn.
• Atarka, World RenderWhenever a dragon you control attacks, it gains double strike until end of turn.
• Reyav, Master SmithWhenever a creature you control that's enchanted or equipped attacks, that creature gains double strike until end of turn.