# How to upgrade heroes and finish a rank-up

Choose the hero to keep, fill its Rank XP with spare heroes, meet its training goal, and check what the promotion will consume.

Official guide: https://www.spacezodiacs.com/guides/starter-upgrading-heroes/
Source checked: 2026-11-04

## How do I rank up a hero?
Open Upgrade and first select the hero you want to keep. Read its training goal and Rank XP bar. Select spare heroes only after choosing that main hero, then review the result before confirming. Consumed heroes leave your roster, so keep useful variants and protect heroes you still use.

Training levels and Rank XP are separate requirements. Training Grounds raises a hero's level. Feeding eligible spare heroes fills Rank XP toward promotion. If the screen says the hero needs training, filling its Rank XP again will not solve that requirement.

## Why is the upgrade button unavailable?
- A hero must meet its current rank's training goal before promotion.
- A hero already at the maximum rank, Z, cannot rank up again.
- You must retain at least three heroes and three different species after the selected spares are consumed.
- Locked heroes cannot be consumed. Read the reason shown for any unavailable spare instead of unlocking your whole roster.
- A full Rank XP bar does not need more spare heroes. Remove extra selections and check the promotion preview.

## Do I need exactly five heroes of the same rank?
No. The current system uses Rank XP rather than a fixed five-hero recipe. Eligible spares can have different ranks, and their contributions differ. The preview shows whether the selected spares fill the required bar. A bar already filled earlier can be promoted without feeding unnecessary extra heroes once the other conditions are met.

## How should I choose spare heroes?
Start with duplicates that do not fill a role you need. Check the full species and variant name; two forms of the same Zodiac can have different skills. Preserve the three-species roster requirement and a working team for the next fight. Check the remaining roster in the preview before confirming.

Auto Fodder can also identify surplus heroes for salvage. Salvage contributes Upgrade Points, not Rank XP. Read the two results separately so you know which selected heroes help this promotion and which are being converted into another resource.