Allied units guide
Companions are allied combat units created by Artifacts, not selectable Costumes. Their value depends on summon scaling, Companion damage, MP, health and the inventory space needed to support them.
Direct answer
The researched character material separates Artifact-created Companions from playable Costumes and NPCs. Confirmed examples include Spirit Mole, Mini Ballista, Electric Jellyfish, Fire Jellyfish, Ice Jellyfish, Mole Captain, and Collin. This is an evidence list, not a claim that the game has a fixed final total.
Planets and other summoned units should be treated as Companion-style build pieces only when the current Artifact or tooltip labels them that way. The supplied material does not prove that every autonomous projectile or orbiting effect uses the same damage, health or revival rules.
Collin
The older guide describes a Collin room where an Artifact connected to the Companion combo can be purchased for 500 Leaves. It also records fixed bargaining power and a token-only shop behavior. That makes Collin useful when the run already supports Companion scaling, but it is not a universal damage upgrade and the current price should be checked in game.
Compare the opportunity cost: a Companion route needs damage scaling, survivability or replacement summons, while a Weapon-only route may use the same inventory slots for direct uptime. Do not treat Collin as a playable co-op teammate or as proof of a guaranteed revive.
Planet builds
The Planet Summoner route in the build library uses Deer, Staff, Telescope and Windsong to create repeated orbiting damage. It is best read as a tested build family, not proof that all Planet effects share one universal Companion formula. Keep the exact Artifact names, version and evidence beside the preset.
If Chaos or elemental Touch effects are part of the route, verify whether the summoned unit counts as eligible damage in the current patch. The Chaos discussion specifically raises Companion interactions but does not provide a developer formula.
Build rules
Prioritize Companion Damage, summon uptime, MP and enough defense to keep the board active. Use the Planet Summoner build as a documented starting point and compare it with the Amethyst Companion build. Both are version-bound examples, not guarantees of current balance.
Related guides
Review the Characters overview, the Artifacts guide, and Chaos and Life Steal mechanics before committing inventory space to an allied-unit route.
Verification note
Last verified against the supplied Sephiria research set. Version-sensitive claims retain their source version; missing paths, compatibility details, and current balance values are marked To be confirmed rather than guessed. See the site's research sources for the full method.
