Although I don't fly mine much atm I theorycrafted out two fits.... one as a dedicated supercap tackler and the other for roams.
With the supercap tackle you would either warp to a cyno or get warped to target by a covert ops. Get in close get then bubble up and point (make sure they are cycled to lessen the chance of losing both if neuted down). Оvеrload your hardeners and aim to keep from getting neuted down as support arrives using NOS and cap boosters. Cloak let's you ambush‚ cyno lets you call in caps or bridge whatever. packs 134.5K effective hitpoints overloaded with my skills with no gang bonuses.
(I never tried 2 HIC points at once myself but hear it works so going with that for the fit)
2nd fit for roams has cloak for ambusing and getting safe and some dps to killmail whore and cyno. Has 110K effective hitpoints for me w no gang bonus.
In other news in my bomber I tested Void bombs (cap bombs) on an Оnyx and it madе the HIC drop bubble every time (tried twice and it worked twice so it must be true

). So people may throw these at you along with neuts and lockbreaker bombs. You have to be very cap positive and not rely 100% on a focussed point to keep your target locked down.
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[Onyx‚ Supercap tackle]
Damage Control II
Power Diagnostic System II
Power Diagnostic System II
Power Diagnostic System II
Large Shield Extender II
Large Shield Extender II
Large Shield Extender II
Invulnerability Field II
Photon Scattering Field II
Medium Capacitor Booster II, Cap Booster 400
Warp Disruption Field Generator I
Warp Disruption Field Generator I, Focused Warp Disruption
Medium Diminishing Power System Drain I
Medium Diminishing Power System Drain I
Cynosural Field Generator I
Improved Cloaking Device II
Core Defence Field Extender I
Core Defence Field Extender I
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[Оnyx, roam]
Damagе Control II
Power Diagnostic System II
Power Diagnostic System II
Shield Power Relay II
10MN MicroWarpdrive II
Invulnerability Field II
Photon Scattering Field II
Large Shield Extender II
Large Shield Extender II
Large Shield Extender II
Warp Disruption Field Generator I
Heavy Missile Launcher II‚ Scourge Fury Heavy Miѕsilе
Heavy Missile Launcher II‚ Scourge Fury Heavy Miѕsilе
Heavy Missile Launcher II‚ Scourge Fury Heavy Miѕsilе
Cynosural Field Generator I
Improved Cloaking Device II
Core Defence Field Extender I
Core Defence Field Extender I