Anyone know if/where I can find one of do I need to use a key? Thank you
Online -> Ultra Evo & Events -> Ingredient Missions -> Pixies & Bottles (Costs 1 Silver Key)
I’ve also found Halobottles in Missions which doesn’t cost any keys. There’s a chance that they’ll appear in dungeons. I didn’t take note of which one exactly though sorry…You could try:
Online -> Missions -> Chapter 2 -> Holy Ruins
Chapter 2,3… -> Ruins, Vallley -> Dungeon. (This also apply to any other ingredient include: Bronze shields, Pixies (any element), Bottles (any element)). There is a small chance to get De-aging fruits in dungeon as well.
For example: Dungeon in Water Ruins,chapter 2 will have chance to get : Bronze Shields, Sea Pixies, Sea Bottles, De-aging fruits.
So in your case, you could fine Halo bottles from Dungeons Holy types.