Pair with an armor stripper. E.g. [Xaku].

With enough range enemies should not outrange your mallet in most rooms. High duration so you don't have to refresh that often.

Str loss from OE is not a big deal due to mallet scaling off enemy damage, armor is the biggest issue.

You could use something else in the exilus slot. Aura mod depends on if you have 100% armor stripper or not. You could grab Growing Power if you have Xaku to strip 100% armor.

About armor srippers:

• [Xaku]: Best overall. Make sure xaku won't slow enemies down. This means that Xaku's 4 should be recasted behind a wall to ensure enemies won't slow down.
• Trinity link: Limited to 3 targets. 100% strip.
• [Mag]: Can't 100% strip with 4, since enemies stop charging your mallet when crushed. 3 might work doesn't strip 100% though.

Arson / Frost eximus:

• These will apply aura that negate your damage. Bring one weapon with radiation so you can rad proc arson/frost. This will make their allies vulnerable.
• [Frost] eximus bubble needs to be popped with a gun, Octavia's mallet won't destroy frost eximus bubble.

Armor stripper weapons:

• Pox: Leaves gas cloud behind for 5 seconds. The cloud applies status.
• Torid: Leaves gas cloud for 10 seconds. The cloud applies status.
• If you have [Xaku], then you can mod for viral instead.