Capacitor Plate because I haven’t been playing captain Grace much lately It scales with Fountain, Rook’s Decree, and Crucible, (as well as providing armor, shield, and cooldown) making it a good generic captain item. On most captains it’s a low priority, but on other heroes who have either a barrier or heal, it is usually a lot more important. I’ve always kind of assumed it would be a must for Grace because of her Ult, but her Ult isn’t actually that useful and she needs to devote slots to CP.
Basically I made an assumption, but haven’t had enough success with her as a captain to work out what build is best.
I might play her as a jungler, but I generally don’t play tanky junglers. Inara is my main (either WP or CP), but if not her then I usually go for another hero with high mobility.
I used to play Grace as a captain a lot, but her scaling is rough due to the need to build CP (with other captains you can typically just build utility items, so your build comes together more quickly), and she doesn’t really offer any advantages. Played as a jungler she’s better, and she’s fine in brawl modes since it’s easier to get full builds there, but as a captain there is a long part of the game where either your holy shields and Ult suffer from not building CC, or your utility and durability suffer from not building utility. As a captain, it’s just too hard to afford the amount of items she needs.