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What if the next Legendary Hero was actually...
Second generation Arvis? His Emperor, armored version. It came to my mind mostly because most of the events until early June (until Bound Hero Battle Seliph & Julia) will be Holy War related (mostly 2nd Gen). Also it could make sense as we already have one villain as a Legendary Hero (L!Grima). He could come with the Fire element, an evolved Valflame, and as another red armored mage.

Fate Grand Order
Dragonball Legends
IV Calc
Heroes