Delivery Moogle + Displacer Kitten + Welding Jar + Black Lotus

How it works

There is at least one additional artifact on the battlefield.
One of the artifacts must be in your hand, while the other is either in your graveyard or in your library.

Cast the artifact in your hand by paying its mana cost.
Displacer Kitten triggers, blinking Delivery Moogle.
When Delivery Moogle enters, it triggers, searching your library or graveyard for the other artifact and putting it into your hand.
Activate the artifact cast in step 1 by sacrificing it.
Repeat.

In which brackets is this combo allowed, per Spellbook's Banned tier?

1–2 · Exhibition & Core

Spellbook classifies this as Banned — not for these brackets.

3 · Upgraded

Spellbook classifies this as Banned — not for these brackets.

4–5 · Optimized & cEDH

Spellbook classifies this as Banned — not for these brackets.