During the next cleanup step, discard cards down to your maximum hand size.
Magmakin Artillerist triggers, dealing 1 damage to each opponent for each card discarded this way.
Curiosity triggers, causing you to draw a card.
As you are still in the cleanup step, once the stack is empty and priority has been passed by all players, you will discard down to your maximum hand size again.
Repeat from step 2.

Near-infinite damage

Infinite self-discard triggers

Infinite draw triggers

Infinite rummaging

Magmakin Artillerist

Curiosity

Proceed to your cleanup step, causing you to discard down to your maximum hand size.
Magmakin Artillerist triggers for each card discarded this way.
Resolve the first Magmakin Artillerist trigger, dealing damage to each opponent.
Kefka triggers, causing you to draw a card for each opponent that lost life.
Repeat from step 3 as needed for all remaining Magmakin Artillerist triggers.
Once all players have passed priority and the stack is empty, you will still be in your cleanup step, and will discard down to your maximum hand size.
Repeat from step 2.

Kefka, Court Mage // Kefka, Ruler of Ruin

Activate Tortured Existence by paying {B} and discarding a creature card.
Magmakin Artillerist triggers, dealing 1 damage to each opponent.
Malcolm triggers, creating a Treasure token for each opponent dealt damage this way.
Resolve the Tortured Existence ability, returning another creature card from your graveyard to your hand.
Activate the Treasure by tapping and sacrificing it, adding {B}.
Repeat.

Infinite damage

Near-infinite colored mana

Near-infinite Treasure tokens

Malcolm, Keen-Eyed Navigator

Tortured Existence

Put a +1/+1 counter on Benthic Biomancer.
Benthic Biomancer triggers, causing you to loot.
Magmakin Artillerist triggers, dealing 1 damage to each opponent and causing you to gain life.
Archangel of Thune triggers putting a +1/+1 counter on each creature you control.
Repeat from step 2.

Near-infinite lifegain

Near-infinite lifegain triggers

Infinite looting

Near-infinite +1/+1 counters

Benthic Biomancer

Archangel of Thune

Activate Collector's Vault by paying {2} and tapping it, causing you to loot and create a Treasure token.
Magmakin Artillerist triggers, dealing 1 damage to each opponent.
Malcolm triggers, creating a Treasure token for each opponent dealt damage this way.
Activate two Treasures by tapping and sacrificing them, adding {2}.
Activate Clock of Omens by tapping two Treasures, untapping Collector's Vault.
Repeat.

Combos with "Magmakin Artillerist"