Well of Lost Dreams

Whenever you gain life, you may pay {X}, where X is less than or equal to the amount of life you gained. If you do, draw X cards.

Hellkite Tyrant

Flying, trample
Whenever this creature deals combat damage to a player, gain control of all artifacts that player controls.
At the beginning of your upkeep, if you control twenty or more artifacts, you win the game.

Ragost, Deft Gastronaut

Artifacts you control are Foods in addition to their other types and have "{2}, {T}, Sacrifice this artifact: You gain 3 life."
{1}, {T}, Sacrifice a Food: Ragost deals 3 damage to each opponent.
At the beginning of each end step, if you gained life this turn, untap Ragost.

Aetherflux Reservoir

Whenever you cast a spell, you gain 1 life for each spell you've cast this turn.
Pay 50 life: This artifact deals 50 damage to any target.

Krark-Clan Ironworks

Farid, Enterprising Salvager

Whenever a nontoken artifact you control is put into a graveyard from the battlefield, create a colorless artifact token named Scrap.
{1}{R}, Sacrifice an artifact: Choose one —
• Put a +1/+1 counter on Farid. It gains menace until end of turn.
• Goad target creature.
• Discard a card, then draw a card.

Magewright's Stone

{1}, {T}: Untap target creature that has an activated ability with {T} in its cost.

Crime Novelist

Whenever you sacrifice an artifact, put a +1/+1 counter on this creature and add {R}.

Treasure Nabber

Whenever an opponent taps an artifact for mana, gain control of that artifact until the end of your next turn.