When Audacious Roughrider enters or leaves the battlefield, exile the top card of your library. Then you may discard a card. If you do, put the exiled card into your hand. If you don't, create a Treasure token.
Wander {4}{R}{R}

Target creature you control gets +2/+0 and gains first strike until end of turn. If it's attacking, create a 1/1 white Human creature token that's tapped and attacking.

You don't lose unspent mana as steps and phases end.
At the beginning of your end step, if you've spent at least five mana to cast spells this turn, draw a card. If you've spent at least ten, create a 10/10 green Elemental creature token. If you spent at least twenty, you gain 20 life. If you spent at least fifty, you win the game.

Up to X target creatures you control each get +1/+1 until end of turn. Untap those creatures.

When Barbarous Roughrider enters or leaves the battlefield, each opponent loses 2 life unless they sacrifice a nontoken creature.
Wander {4}{B}{B}

Flash
At the beginning of your end step, if you've cast no spells this turn, you may draw a card, then discard a card.

Spells you cast and abilities you activate that target equipped creature cost {2} less. This ability can't reduce the mana in that cost to less than one mana.
Equipped creature gets +1/+1 and has lifelink.
Equip {2}

Ruins you control can't be blocked by creatures with power 2 or less.
{1}, {T}: Put a +1/+1 counter on target Ruin.
Spellcharge 5

Equipped creature gets +1/+2 and has “At the beginning of your end step, put a time counter on Blade of Bright Futures.”
{2}, Sacrifice Blade of Bright Futures: You gain X life and draw X cards, where X is one plus the number of time counters on it. Activate only as a sorcery.
Equip {2}

Equipped creature gets +2/+1 and has “At the beginning of your end step, put a time counter on Blade of Clouded Pasts.”
{2}, Sacrifice Blade of Clouded Pasts: Target player loses X life and discards X cards, where X is one plus the number of time counters on it. Activate only as a sorcery.
Equip {2}

Whenever an attacking creature you control dies, Bleeding Edge Memorial deals 1 damage to defending player.
Spellcharge 4

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.

Choose one or both —
• Target creature you control gets +1/+1 until end of turn.
• Create a 1/1 white Human creature token.

Flying
When Breaching Jaxl enters, untap target nonland permanent.
Wander {2}{U}

Trample
Breaking Ground must be blocked if able.
{T}: Add {C}.
Spellcharge 9

You may cast this spell by paying {1}{R}{R} and exiling X cards with flashback from your graveyard rather than paying its mana cost.
Bring Down the Sky deals X damage to each creature and each planeswalker.

This spell costs {4} more to cast if it's your turn.
Return target nonland permanent to its owner's hand. If it's your turn, return up to two target nonland permanents to their owners' hands instead.

Search your library for a basic land card, reveal it, put it into your hand, then shuffle. If this spell's flashback cost was paid, instead search your library for any number of land cards, put them onto the battlefield tapped, then shuffle.
Flashback {3}{W}{U}{B}{R}{G}

Reach
Bumbling Bigfoot doesn't untap during your untap step.
Wander {1}{G}{G}

All spells cost {1} more to cast.
Spellcharge 6

When Cairnblade of the Ancients enters, destroy target creature an opponent controls.
Equipped creature gets +4/+2 and has vigilance.
Equip {4}

Wander {2}{W}{W}
[–1]: Create your choice of a 1/1 white Bird creature token with flying or a 2/2 black Cat creature token.
[–2]: If a permanent entering the battlefield under your control this turn causes an ability of a permanent you control to trigger, that ability triggers an additional time.
[–3]: Put a +1/+1 counter on each creature you control.

{T}: Target player exiles a card from their graveyard.
{2}, {T}: Exile target card from a graveyard. Then if there are three or more cards exiled with Censor Tablet, exile it. If you do, draw two cards.