If you are unable to use the Minotaur Vessel summon skill in Metaphor: ReFantazio, there are several potential reasons and steps you can take to troubleshoot the issue:

1. Check Vessel Compatibility:
– Ensure that the Minotaur Vessel is compatible with your current Summoner Archetype. Some Vessels can only be used by specific Archetypes.

2. Verify Talisman Usage:
– Confirm that you have the correct talisman required for the Minotaur Vessel. Each Vessel is associated with specific talismans, and using the wrong talisman can prevent the Vessel from being summoned.

3. Check Eupha’s Special Experiment:
– Ensure that Eupha is available at the Akademia and that you have completed her Special Experiment to craft the Minotaur Vessel. If you have already crafted the Vessel but are still unable to summon it, there might be an issue with your party setup or skills.

4. Review Party Setup and Skills:
– Check your party’s composition and skills. Some Vessels may require specific skills or allies to be summoned effectively. For example, some Synthesis skills require certain Lineages or skills to be active.

5. Update Your Game:
– If you are playing an older version of the game, there might be updates that fix issues related to Vessel summoning. Regularly check for updates from the game developers, as they often add new content and fix bugs.

By following these steps, you should be able to identify and resolve the issue preventing you from using the Minotaur Vessel summon skill in Metaphor: ReFantazio.