This spell costs less to cast for each creature card you own in exile and in your graveyard.
Menace, deathtouch

Flying
When this creature leaves the battlefield, create a Food token. (It's an artifact with ", , Sacrifice this token: You gain 3 life.")

: Target creature you control gets +1/+1 and gains haste until end of turn. Activate only as a sorcery.

, Sacrifice a token: Draw a card.

Delirium — This creature can't attack or block unless there are four or more card types among cards in your graveyard.
At the beginning of your upkeep, you may mill a card. (You may put the top card of your library into your graveyard.)

This creature gets +1/+0 for each other Rat you control.
Threshold — Whenever you attack with one or more Rats, if there are seven or more cards in your graveyard, you may pay . If you do, return this card from your graveyard to the battlefield tapped and attacking.

Flash
When this Vehicle enters, target creature or Vehicle gets +2/+0 until end of turn.
Crew 1 (Tap any number of creatures you control with total power 1 or more: This Vehicle becomes an artifact creature until end of turn.)

Flying, ward (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays .)
This creature's power is equal to the number of noncreature, nonland cards in your graveyard.
When this creature dies, if there's a Lesson card in your graveyard, draw a card.

Equipped creature gets +2/+0 and has "Whenever this creature attacks alone, you draw a card and lose 1 life."
Equip (: Attach to target creature you control. Equip only as a sorcery.)

Menace (This creature can't be blocked except by two or more creatures.)
Discard a card, Sacrifice this creature: Draw a card.

This creature enters prepared. (While it's prepared, you may cast a copy of its spell. Doing so unprepares it.)

Landfall — Whenever a land you control enters, this creature gets +2/+2 until end of turn.

Tap target creature or Vehicle, then put three stun counters on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)
Cycling (, Discard this card: Draw a card.)

When this enchantment enters, exile target nonland permanent an opponent controls until this enchantment leaves the battlefield.

Landfall — Whenever a land you control enters, this creature gains flying until end of turn and you gain 1 life.
Plainscycling (, Discard this card: Search your library for a Plains card, reveal it, put it into your hand, then shuffle.)

As long as you control a token, this creature gets +2/+0 and has trample.

When this creature enters, look at the top X cards of your library, where X is the number of creatures you control. Put one of those cards into your hand and the rest into your graveyard.

You may pay and exile a creature card from your graveyard rather than pay this spell's mana cost.
Flying

, , Discard a card: Draw a card for each card you've discarded this turn.

This creature enters with a +1/+1 counter on it for each creature card in your graveyard.
Whenever one or more creature cards are put into your graveyard from anywhere, put that many +1/+1 counters on this creature.