How to use hallowed grail

[Nix]

Title says it all.. I cannot find a way to activate the hallowed grails you get from lilim battles.. Any tips?

[Slashley]

On Demon Battle screen, topright is
Day x
(Burst) Time Remaining
--:--
buff icons
Apply Effect

The Apply Effect button is where you can spend Grails. Please note that you'll lose them all at next reset and that only Union leader, Sub-leaders and Officers can spend the Grails. Grails are Union-wide after all, and all Grails earned by all members of the Union are given to the Union.

[Laventale]

There are two threads where you could ask that, please, refrain from creating threads with questions that can be easily answered elsewhere.