Ashling, the Limitless | Catalyst Elemental | Grave Sifter

(and one other card)

Grave Sifter in hand.
Catalyst Elemental in your graveyard.
Ashling and
Urza's Incubator on the battlefield (
Urza's Incubator with "Elemental" chosen).

Cast
Grave Sifter for its evoke cost by paying ({2} magic symbol) due to
Urza's Incubator.
When
Grave Sifter enters, its first ability and evoke abilities trigger.
Resolve the first trigger, returning
Catalyst Elemental from your graveyard to your hand.
Resolve the second trigger, sacrificing
Grave Sifter.
When
Grave Sifter dies,
Ashling triggers, creating a token copy of
Grave Sifter with haste.
When the
Grave Sifter token enters, it triggers, returning
Grave Sifter from your graveyard to your hand.
Cast
Catalyst Elemental by paying ({R} magic symbol) due to
Urza's Incubator.
Activate
Catalyst Elemental by sacrificing it, adding ({R} magic symbol) ({R} magic symbol) .
When
Catalyst Elemental dies,
Ashling triggers, creating a token copy of
Catalyst Elemental with haste.
Activate the
Catalyst Elemental token by sacrificing it, adding ({R} magic symbol) ({R} magic symbol) .
Repeat.

If you have at least ({2} magic symbol) ({R} magic symbol) in your mana pool on a particular iteration, step 10 can be skipped.