Should I upgrade Rainbow in Slay the Spire 2?

Compare the upgraded text: Channel 1 Lightning. Channel 1 Frost. Channel 1 Dark.. If the upgrade lowers cost, adds damage/block, or enables a combo piece, it is usually high priority.

What builds use Rainbow?

Rainbow appears in 2 tracked builds: Overcharge Detonation (A-tier, flex pick), Umbral Engine (A-tier, core card).

What character uses Rainbow?

Rainbow is tagged as a Defect card. See the Defect build hub for archetypes that care about it.

Updated for Data 2026-03-17Early Access — numbers may shift with patches.

Rainbow

Defect · Skill · Rare · 2 cost

Base

Upgraded

Card text

Channel 1 Lightning. Channel 1 Frost. Channel 1 Dark. Exhaust.

Rainbow+

Channel 1 Lightning. Channel 1 Frost. Channel 1 Dark.

Builds that use Rainbow

Archetypes that draft this card in real runs, with the role it plays.

Keywords

Exhaust Channel Lightning Frost Dark

Build context

See the Defect build hub for archetypes that feature this card in real runs.

Related cards

Rainbow FAQ

Should I upgrade Rainbow in Slay the Spire 2?: Compare the upgraded text: Channel 1 Lightning. Channel 1 Frost. Channel 1 Dark.. If the upgrade lowers cost, adds damage/block, or enables a combo piece, it is usually high priority.
What builds use Rainbow?: Rainbow appears in 2 tracked builds: Overcharge Detonation (A-tier, flex pick), Umbral Engine (A-tier, core card).
What character uses Rainbow?: Rainbow is tagged as a Defect card. See the Defect build hub for archetypes that care about it.

Patch history

SpireForge snapshots card text from Untapped exports dated 2026-03-17. When Mega Crit ships a balance patch, we re-run the scraper and refresh every affected URL—see /patches for the editorial log.