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

Unstable Formation enters with three charge counters on it.
{1}, {T}, Remove a charge counter from Unstable Formation: Unstable Formation deals 1 damage to target player or planeswalker. You may sacrifice Unstable Formation. If you do, draw a card.

{T}: Add {C}.
Whenever Unwavering Gates attacks, other creatures you control gain indestructible until end of turn.
Spellcharge 5

When Ursine Advocate enters, create a 2/2 green Bear creature token.

Valley Caravan's power and toughness are each equal to the number of creatures you control.
Wander {3}{W}{W}
When Valley Caravan enters, if it wandered, create a 1/1 white Human creature token.

Spellcharge 2
When Vanquished Conqueror dies, draw a card.

Equipped creature gets +2/+2.
Equip {2}
Spellcharge 4

When Vorpal Titan enters, destroy all nonbasic lands.

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}

Target artifact or creature you control becomes an artifact creature with base power and toughness 5/5 until end of turn.

Enchant artifact or land
Enchanted permanent has “{T}: Add one mana of any color.”
Whenever enchanted permanent becomes a creature, untap it.
Wander {2}{G}

Target creature can't be blocked this turn. If this spell's flashback cost was paid, put a +1/+1 counter on that creature.
Flashback {1}{U}

You gain 4 life. If this spell's flashback cost was paid, draw a card.
Flashback {3}{W}

Vigilance
{T}: Scry 1.
Spellcharge 5

{T}: Add {C}.
Whenever Wasted Watchpost deals combat damage to a player, you may sacrifice it. When you do, destroy target nonbasic land that player controls.
Spellcharge 3

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

Creatures your opponents control get -1/-0.
Spellcharge 5

At the beginning of combat on your turn, if you've spent at least five mana to cast spells this turn, creatures you control get +1/+1 and gain trample until end of turn.

At the beginning of your end step, you gain 1 life.
Whitecliff Guardian gets +0/+1 for each 1 life you have above your starting life total.

Whenever a creature entering the battlefield under your control causes an ability of a permanent you control to trigger, draw a card. This ability triggers only once each turn.

Create X 1/1 white Insect creature tokens with flying.
Flashback—{3}{W}{W}, Tap X untapped creatures you control.

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

Choose creature or land. Reveal the top four cards of your library. Put all cards of the chosen type revealed this way into your hand and the rest into your graveyard.

Tap up to one target creature. Creatures you don't control don't untap during their controllers' next untap step.
Flashback {4}{U}

When Writheling enters, 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.