Mage Slayer

Whenever equipped creature attacks, it deals damage equal to its power to the player or planeswalker it's attacking.
Equip {3}

Harmonize

Beast Within

Destroy target permanent. Its controller creates a 3/3 green Beast creature token.

Steel Hellkite

Flying
{2}: This creature gets +1/+0 until end of turn.
{X}: Destroy each nonland permanent with mana value X whose controller was dealt combat damage by this creature this turn. Activate only once each turn.

Fierce Empath

When this creature enters, you may search your library for a creature card with mana value 6 or greater, reveal it, put it into your hand, then shuffle.

Xenagos, the Reveler

+1: Add X mana in any combination of {R} and/or {G}, where X is the number of creatures you control.
0: Create a 2/2 red and green Satyr creature token with haste.
−6: Exile the top seven cards of your library. You may put any number of creature and/or land cards from among them onto the battlefield.

Etali, Primal Storm

Whenever Etali attacks, exile the top card of each player's library, then you may cast any number of spells from among those cards without paying their mana costs.

Cinder Glade

({T}: Add {R} or {G}.)
Cinder Glade enters tapped unless you control two or more basic lands.

Elvish Mystic

Temple of the False God

{T}: Add {C}{C}. Activate only if you control five or more lands.

Natural Connection

Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Archetype of Aggression

Creatures you control have trample.
Creatures your opponents control lose trample and can't have or gain trample.

Flametongue Kavu

When Flametongue Kavu enters, it deals 4 damage to target creature.

Combustible Gearhulk

First strike
When Combustible Gearhulk enters, target opponent may have you draw three cards. If the player doesn't, you mill three cards, then Combustible Gearhulk deals damage to that player equal to the total mana value of those cards.

Fires of Yavimaya

Creatures you control have haste.
Sacrifice Fires of Yavimaya: Target creature gets +2/+2 until end of turn.

End-Raze Forerunners

Vigilance, trample, haste
When End-Raze Forerunners enters, other creatures you control get +2/+2 and gain vigilance and trample until end of turn.

Myriad Landscape

Myriad Landscape enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice Myriad Landscape: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Rattleclaw Mystic

{T}: Add {G}, {U}, or {R}.
Morph {2} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When Rattleclaw Mystic is turned face up, add {G}{U}{R}.

Kessig Wolf Run

{T}: Add {C}.
{X}{R}{G}, {T}: Target creature gets +X/+0 and gains trample until end of turn.

Siege Behemoth

Hexproof
As long as Siege Behemoth is attacking, for each creature you control, you may have that creature assign its combat damage as though it weren't blocked.

Dawnglade Regent

When Dawnglade Regent enters, you become the monarch.
As long as you're the monarch, permanents you control have hexproof.

Berserkers' Onslaught

Attacking creatures you control have double strike.

Sakura-Tribe Elder

Sacrifice Sakura-Tribe Elder: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Mountain

Ram Through

Target creature you control deals damage equal to its power to target creature you don't control. If the creature you control has trample, excess damage is dealt to that creature's controller instead.