Whenever you cast an artifact spell, investigate. (Create a Clue token. It's an artifact with ", Sacrifice this token: Draw a card.")
Activated abilities of artifacts you control cost less to activate. This effect can't reduce the mana in that cost to less than one mana.

Flying, trample
Whenever an opponent searches their library, that player sacrifices a creature of their choice and loses 10 life.
Whenever another creature dies, put a +1/+1 counter on Ob Nixilis.

Prevent all combat damage that would be dealt this turn.

When this enchantment enters, create X 1/1 colorless Hero creature tokens.
Light Party — Whenever you attack with four or more creatures, scry 2, then draw a card.
Full Party — Whenever you attack with eight or more creatures, those creatures get +4/+4 until end of turn.

Whenever you draw a card, put a +1/+1 counter on this creature.
When this creature dies, create X 1/1 blue Squid creature tokens with islandwalk, where X is the number of +1/+1 counters on this creature. (They can't be blocked as long as defending player controls an Island.)

When The First Doctor enters, search your library and/or graveyard for a card named TARDIS, reveal it, and put it into your hand. If you search your library this way, shuffle.
Whenever you cast a spell with cascade, put a +1/+1 counter on target artifact or creature.

This land enters tapped unless you have two or more opponents.
: Add or .

Deathtouch
You may look at the top card of your library any time.
You may play lands and cast spells with mana value 4 or greater from the top of your library.
: Surveil 2.

Whenever a player casts an instant or sorcery spell, if that spell targets only this creature, copy the spell for each other creature that spell could target. Each copy targets a different one of those creatures.

Whenever this creature attacks, defending player mills ten cards.

When this creature enters, sacrifice another creature. You gain X life and draw X cards, where X is that creature's power.

: Add .
, , Sacrifice a creature: Put a soul counter on this land. Then if there are three or more soul counters on it, remove those counters, transform it, then untap it. Activate only as a sorcery.

Prowess
If a source you control would deal noncombat damage to a creature an opponent controls, put that many -1/-1 counters on that creature instead.

Menace, haste
Whenever this creature attacks, it deals 1 damage to each of up to one target creature, up to one target player, and/or up to one target planeswalker.
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for or one mana of that creature's color.)
Any number of target nonland permanents you control phase out. (Treat them and anything attached to them as though they don't exist until your next turn.)

Flying, deathtouch
When this creature enters, draw a card.

As an additional cost to cast this spell, sacrifice a creature.
Add .

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for .)
Search your library for an artifact card with mana value X or less, put it onto the battlefield, then shuffle.

Those Who Came Before — This spell costs less to cast for each historic card in your graveyard. (Artifacts, legendaries, and Sagas are historic.)
Exile any number of historic cards from your graveyard with total mana value 30 or greater: You get an emblem with "Creatures you control have base power and toughness 9/9."

Suspend 3—
Each player exiles all creature cards from their graveyard, then sacrifices all creatures they control, then puts all cards they exiled this way onto the battlefield.