Aura Forma for Aura.
Add a forma to your exilus for a little more versatility with free slot, [Power Drift] in my case.
Built for Merulina cruising, spamming 1 and 4 for CC and damage along with pistol usage.
Keep 2 and 3 on all the time, shouldn't have much energy problems.
Replace Stretch with (Umbral) Vitality and/or [Pistol Amp] with [Brief Respite] for Survivability.

Seems to handle higher enemies in Simulacrum, but you want a good pistol, like a [Kuva Nukor], [Sporelacer] secondary Kitgun, [Pyrana] Prime, etc. Great for low level runs.

As of time of writing:

Sea Snares:
16.25 drain
43.5 Range
11.4s Duration
645 Damage/s
206.4 Damage increase/s

Merulina:
16.25 drain
19,350 Health
75% Damage Reduction

Aquablades:
48.75 Drain
23.75s Duration
645 Damage

Riptide:
65 Drain
17.4 Range
17.4 Radius
6450 Damage