Best Helminth for Excalibur Umbra?

[The Hoss Behind the Slaughter]

I really enjoy Excalibur Umbra, partly because he still does his own thing when you're in a Necramech. However, his 3rd ability is kind of redundant since his 4th just... exists. What's the best ability to replace it with? I was leaning towards either Roar, Warcry, or Dispensary, but there are some frames that I never really use so I wouldn't know if their ability would work well on Excal Umbra.

[Ciulla]

Empower is a good, low-investment choice on him because it gives a 50% power strength boost to his next 4 cast for as long as you keep that cast active.

Other good options are Warcry (Valkyr), Rest & Rage (the Rage version, Equinox), Eclipse (if you can deal with its damage buff being inconsistent, Mirage), Roar (Rhino), and Breach Surge (Wisp).

Out of the options, I'd lean towards Breach Surge and Rage being the strongest due to them being multiplicative damage bonuses applied to total damage after mods. Warcry is probably the next best option. Roar and Eclipse aren't the best due to the penalty to the damage bonuses they receive through the Helminth system, but are still usable.

Of particular note is the synergy Excalibur has with Breach Surge, wherein blinded enemies always release a surge spark, and Excalibur has on-demand blind through his second skill.

TL;DR: In my opinion Breach Surge is probably his best option, followed closely by Rage from Rest & Rage. The third best is Warcry, and Roar/Eclipse/Empower are fourth place, with Empower possibly edging out the first two options in fourth place depending on your total power strength before its bonus.

[The Big Brzezinski]

Shuriken with the Seeking Shuriken augment is a fine way of removing armor from a troublesome Grineer heavy. Throw it with 1, Radial Howl, and remove the piece from the board.

[NikemanBOOM]

I've enjoyed using Oberon's Smite with Smite Infusion for added Rad damage on top of giving Umbra a bit more support capability as well as another status type.

[Pakaku]

Special mention to Dispensary for team-support, and you probably have a ton of Protea parts if you've been farming the Granum Void

[Dante Ironclaw]

Could also go xaku's whisper to be the ultimate anti-sentient frame