Quick answer
  • A Rein is an unlock item: its description says to use it to permanently unlock the named minion. Select the minion afterward in the minion panel.
  • If the game warns that the Rein is tradable, decide whether you want the unlock before consuming it. Do not assume you can sell the same item after using it.

What does using a Rein actually do?

The official descriptions for Lord of the Crimson Vale and Serparmat the Devourer both say the Rein permanently unlocks the named minion. This separates the item in your inventory from the companion it adds to your collection. A Rein is not a rune to socket into equipment.

Read the name and effects

Check that it is the minion you want, particularly when choosing between sustain and damage bonuses.

Decide whether to consume it

Stop at a tradability warning if you are still weighing an unlock against keeping the item for trade.

Use it, then select the minion

After a successful unlock, the community-reported follow-up is to open the lower-right minion panel and equip the companion on the carriage.

Why the game warns before you use it

An October 6 Lord of the Cinder thread describes the warning clearly. A reply explains that the unused Rein can be sold, but using it removes that sale option. The buyer chose to unlock it anyway. That is a choice between keeping a tradable item and adding a companion, not a reason that every player should sell every rare drop.

Before confirming the unlock
SituationSensible next step
You want the minion for your active buildRead its effect, then accept that using the item may end its resale option.
You already have the unlockCheck whether this is a duplicate and inspect its actual trade status.
You are undecidedKeep the item unused while comparing its benefit with your current minion.
A guide quotes an old priceUse the current listing in your own currency; an old sale price is not a guaranteed return.

Duplicates, filters and auto-sell are not the same thing

The launch Reins thread contains conflicting trade advice, including broad claims that Reins cannot be sold. Later discussion of a specific legendary directly contradicts that blanket claim. Use the actual item’s trade status rather than applying a rule about one rarity to the entire item category.

In an October 4 auto-sell thread, replies distinguish equipment auto-sell from Rein pickup: they say unlocked Reins may be ignored or carried according to the relevant settings. The official October 2 patch separately states that Legendary Reins are always picked up regardless of filter settings. These statements address different parts of the loot process.

Requirements and limits to check

Reins unlock their named minions permanently. A complete list of per-Rein level requirements remains unconfirmed, so check the item before using it. A monster’s level, a vendor’s location or a video of the drop does not by itself establish a character requirement.

If using the item makes a sound but you see no new companion, check selection before trying to obtain another copy. If the drop is not collected, check free cargo space and the duplicate setting. Neither symptom by itself proves the Rein was lost or that a second unlock is required.

Sources and scope

Steam release; retained sources checked 9 October 2026. Patch-specific rules and player reports are identified where relevant. No hands-on verification.

Review status
Source-reviewed
Game version
Steam 1.0.x; source-specific dates and patch scope
Checked
Method
Article-specific retained-source review and editorial revision; current gameplay not tested. Retained source bundle checked for this release; no current-client gameplay test.
  1. Rein of the Lord of the Crimson Vale — Steam Community Market first-party

    Permanent named minion unlock.

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  2. Rein of the Serparmat the Devourer - Steam Community Market first-party

    Permanent named minion unlock.

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  3. Lord of the Cinder Legendary Rein :: Deskrawl: Idle ARPG General Discussions community

    Player explanation of use-versus-trade warning.

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  4. Can't use minion :: Deskrawl: Idle ARPG General Discussions community

    Equip after using a minion unlock.

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  5. Reins drop rate? community

    Conflicting early trade advice and duplicate discussion.

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  6. Can i still drop blue/yellow minion rein if i have those rarities on auto sell? :: Deskrawl: Idle ARPG General Discussions community

    Players distinguish equipment auto-sell from Rein pickup.

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  7. Deskrawl: Idle ARPG — Official Announcements first-party

    Official Legendary pickup override.

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  8. can't auto pickup Minions when it drops.. :: Deskrawl: Idle ARPG General Discussions community

    Cargo and duplicate-pickup troubleshooting.

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