Ok I know you want to buff Dzhaggernaut's HP, but there are more ideas such as...
Activating all types of OD (what I mean is Juggernaut will not only have instant healing: from Wasp to Mammoth's OD as a whole).
The A-Bomb will deal 100k damage and the J-boss will be invulnerable to his/her own explosion. Blast radius will be 50 meters.
Terminator capable of ignoring all type of defence when OD activated. This means.... Titan's Force Field, Double Armor AND Mammoth's invulnerability. Last 15 seconds.
No firing delay when firing the Railgun (Firerate will boosted to 0.2 second reload time when OD is active). Striker shots will be affected to (Reduce locking time to 1 second and fire a barrage of 12 when OD is active). Last 5 seconds.
Stun any tanks and effectively shut down attacker's Overdrives (including Mammoth's). EMP radius will remain the same and last 6 seconds.
As usual, heal his/her HP to full and triggers a powerful shockwave.
Greatly reduce incoming damage by 90% and heal him/her by 1% of HP per tick (each tick will be 0.2 seconds). Last 5 seconds.
Crush any tanks instantly you touch and deal 9,999 damage per tick (a tick for this case its 0.1 seconds).
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Terminator gain several abilities and buffed parameter:
Railgun shot will have Hyperspace Round's behavior. At the mean time, it also gain healing. Deal 3k damage will heal 3k HP. Deal fatal blow will double your healing.
Its firing delay reduced to 0.5 second and reloading reduced to 1 second.
Striker itself too will gain the hit-and-heal.