There's a specific strategy utilizing [Nyx]'s Absorb, Specters, and [Chroma]'s Vex Armor to nuke Defense missions all the way up to the level cap. This build works to try and fill a support role. We subsume an additional buff or QoL ability to make the runs more consistent.
Nourish and Empower increase weapon damage so that [Nyx]'s Absorb can be boosted to adequate levels. Dispensary should be chosen if you're having issues with energy but it needs more duration to break even on it's cost.
Reckoning is replaced as it serves no purpose on this build. The other three abilities at least contribute damage or protection.
[Energy Siphon] helps everyone to keep their energy economy in check. This is especially important for the [Nyx]. Due to the nature of how the strategy is run you really don't have many aura options.
Survivability from [Rolling Guard] and [Phoenix Renewal] allows [Oberon] to roam around the map. The primary purpose of this is to leash energy orbs with [Vacuum] to proc your Arcane Energize near the [Chroma]. This way he can stay within range of the specter.
Arcane Aegis allows you to roam freely when it procs. It can be replaced with any other arcane to suit your playstyle.