Purge spell, get upgraded version later (event)

[Aquiem]

If you select an already upgraded spell does it remove what you picked and replace them with something else? Is it better to use a spell that hasn't been upgraded already? (likewise with the purge unit option?)

[Limdood]

It will add to the spell/unit, while keeping any existing upgrades. The spell/unit will be gone for (at least) 2 battles, with the option to have it gone for longer for an even better upgrade.

Note that the upgrade given by the event takes up an upgrade slot if one is available, so upgrading a spell/unit that hasn't been upgraded yet will leave you one less custom upgrade for you to choose later.

Also note that if the spell/unit already has all of its upgrade slots filled, you will still get an upgraded spell/unit, and that spell/unit will have a bonus slot, filled with the upgrade from the event.

The event always only uses 1 upgrade slot, no matter if you tell the guy to hold on to the unit/spell for even longer or not.