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.

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

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.

This spell can't be countered.
Haste
Whenever an opponent casts a spell during your turn or spends at least five mana to cast a spell, Aspirant's Bane deals 5 damage to that player.

Create a tapped 2/1 red Human Warrior creature token.
Flashback {2}{R}

Enchant creature
Enchanted creature gets +2/+0 and has “Attacking creatures you control get +1/+0.”
Wander {2}{R}

Flash
When Zyxthax Apex enters the battlefield, each opponent loses 3 life and you gain 3 life.
When Zyxthax Apex leaves your graveyard, each opponent loses 3 life and you gain 3 life.

When Writheling enters the battlefield, exile up to one target card in a graveyard. If you do, each opponent loses 1 life and you gain 1 life.
When Writheling leaves your graveyard, draw a card.

When Widowed Maiden enters the battlefield, return target creature card from your graveyard to your hand.
Spellcharge 3

Lifelink
When Weathered Blackguard enters the battlefield, you may attach target Equipment you control to it.
Wander {2}{B}

Target player discards two cards and loses 2 life. If this spell's flashback cost was paid, instead that player discards a card and loses 1 life.
Flashback {B}

Search your library for a card, put it into your hand, then shuffle.
Flashback—{1}{B}, Discard a card, Sacrifice a creature.

Destroy target creature. If that creature entered the battlefield this turn, scry 2.

When Thornlasher Mortis enters the battlefield, mill two cards.
Whenever one or more cards leave your graveyard, create a 1/1 green Saproling creature token. This ability triggers only once each turn.

Whenever Skarni Raider attacks, if it's equipped, you draw a card and you lose 1 life.

When Skarni Patrol enters the battlefield, if you control an Equipment, you draw a card and you lose 1 life.
Pay 2 life: The next equip ability you activate this turn costs {2} less to activate. Activate only once each turn.

When Rib Collector enters the battlefield, if it wandered, return target creature card from your graveyard to your hand.
Wander—{1}{B}, Sacrifice another creature.

Flying
Equipped creature gets +2/+0.
Equip {2}
Spellcharge 2

Return target artifact or creature card from your graveyard to the battlefield.
Flashback—{3}{B}, Sacrifice a creature.

Enchant creature
Enchanted creature gets +1/+1 and can't block.
Wander {1}{B}

When Phyto's Offshoot enters the battlefield, you may exile any number of permanent cards from your graveyard. When you do, target opponent reveals that many cards from their hand. You choose one of them. That player discards that card.
When Phyto's Offshoot leaves your graveyard, exile all cards from your opponents' graveyards.

Exile target creature or planeswalker. Its controller loses 2 life.

You lose life equal to the number of cards you've drawn this turn, then draw a card. You may repeat this process any number of times.

Exile target creature. Create a token that's a copy of it except it's a Ruin artifact instead of its other types and it has spellcharge X, where X is its mana value.

Flash
When Hazard Blade enters the battlefield, destroy target creature an opponent controls that was dealt damage this turn.
Equipped creature get +4/+0.
Equip {5}