Displacer Kitten + Mana Echoes + Gemstone Array + Emeritus of Truce // Swords to Plowshares

How it works

Cast the copy of Swords to Plowshares from exile by paying its mana cost.
When you cast that spell, Displacer Kitten triggers, flickering Emeritus of Truce.
When Emeritus of Truce // Swords to Plowshares enters, it and Mana Echoes triggers.
Resolve the Emeritus of Truce trigger, causing an opponent to create a 1/1 Inkling creature token with flying and preparing Emeritus of Truce.
Resolve the Mana Echoes trigger, adding at least since Displacer Kitten and Emeritus of Truce are both Cats.
Resolve Swords to Plowshares, exiling a creature an opponent controls and causing them to gain life.
Activate Gemstone Array by paying , adding one colored mana.
Repeat any number of times.
If the board state allows, create an Inkling token in step 4 instead of targeting an opponent.

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

1–2 · Exhibition & Core

Allowed in this bracket.

3 · Upgraded

Allowed in this bracket.

4–5 · Optimized & cEDH

All combos are allowed.