The Fox outfit looks pretty strong to me. The added bonus of the 4* healing outfit being linked to it, makes rolling for it extra good. The heal does have a fairly long cooldown to balance it. Unfortunately the in game tutorials don't seem to be that clear on how to activate the "focused" heal as opposed to the normal heal.

Double dash, AoE "ultimate" ability. Assuming cooldowns tick down while the ultimate is active, it can possibly be used to stall (for the healing outfit's cooldown.)

Defensively, it is great as it effectively increases Nikki's max health from 5 to 7, because it heals 2 if Nikki is reduced to 0 HP.

So definitely roll for it if you want combat buffs. That said, combat in this game isn't that difficult, so it isn't necessary to obtain it to beat the main story etc. It is just a nice to have combat upgrade if you can afford to roll for it.