Legendary Creature — Merfolk Wizard
Affinity for artifacts (This spell costs less to cast for each artifact you control.)
When Emry enters, mill four cards.
: Choose target artifact card in your graveyard. You may cast that card this turn. (You still pay its costs. Timing rules still apply.)
1/2

Another blue artifact-matters commander generating value from artifacts.

Blue artifact synergy engine that taps artifacts for mana and casts spells.

Tutors small artifacts to recur with Emry's recast ability.

Cheap artifact that fuels affinity and can be recast from yard.

Artifact ramp that reduces Emry's cost and recurs from graveyard.

Similar artifact recursion engine swapping artifacts from graveyard.

Tutors three-mana artifacts to be reused by Emry.

Cast artifacts from top of library, pairing with artifact recursion themes.
→ You control one opponent on each of their turns, Lock
→ Infinite storm count, Infinite card draw at the beginning of the next upkeep, Infinite draw triggers at the beginning of the next upkeep
→ Prevent all damage that would be dealt to you, You have protection from everything, Lock
→ Infinite turns, Lock
→ Infinite colored mana, Infinite storm count
→ Infinite turns, Lock
You'll still pay all costs for a spell cast this way, including additional costs. You may also pay alternative costs if any are available.
To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases, then apply any cost reductions (such as that of Emry). The mana value of the spell remains unchanged, no matter what the total cost to cast it was.
Once you announce that you're casting a spell, no player may take actions until the spell has been paid for. Notably, opponents can't try to change by how much Emry's cost is reduced.
Casting the target card causes it to leave your graveyard and become a new object. You can't cast it again if it returns to your graveyard this turn.
If Emry's last ability targets an artifact land card, you can't play it. Effects that allow you to "cast" a card don't allow you to play a land card.
The cost reduction ability reduces only the generic mana in Emry's cost. The colored mana must still be paid.
You must follow the normal timing permissions and restrictions for the target artifact card. Unless it has flash, you'll most likely only be able to cast it during your main phase while the stack is empty.