Cloaking field passive ability cloaks all nearby friendly units, but not itself. A popular strategy is to attach arbiters and observers to a carrier group. The carriers attack from under the cloak, and ward off attacks on the uncloaked arbiters.
Stasis ability can cut an enemy attack wave in half, allowing allied forces to eliminate foes in smaller, more manageable groups. A popular strategy is to use stasis to disable high threat units, like siege-tanks or devourers, while destroying weaker enemies.
Recall ability offers a powerful means of strategic movement. Arbiters may use recall to teleport allied forces into an enemy base, circumventing any defenses. Recall is of particular importance as the campaign does not allow the player to use warp prisms or other transports, making Recall the only reliable way to remotely move forces around the map.
The arbiter is much more of an offensive-support craft than the void ray and destroyer, but its force-multiplier abilities remain effective when used correctly. While the mothership is also available in the campaign, the player is still limited to only one, but may have multiple arbiters.