Viscera Nanobot + Self Destruct

[Your Neighbour]

I usually use an unpiloted mech as a fast boss killing device, happened to have Viscera Nanoboat (Gives HP on kills), turns out self destruct actually counts those as kills as well, so you can literally do unlimited self destruct for instant kills.

[Brosef Iosif]

Yes, this is the one and only where this is absolutely free and perfect, an absolute must-grab if you have viscera nanobot somehow and yet another reason why Nano Mech is stupidly overpowered. You can only use Self-Destruct once per mission though...
In fact, this is exactly the same rationale as the damage inflicted weapons of the Hazardous Mechs, hence why they are called necromechs sometimes. You can kill yourself with them, as long as you kill a vek, you are brought back. That's why it's doubly useful on Unstable Mech who can get collision damage behind while striking in front, if you do it while having a single HP, that's totally worth it as you'll regenerate with one (or more) anyway!

[Jyles-Jin]

External sources of healing like Repair Field and Repair Drop will also revive fallen mechs, as long as the mech is still standing at the end of the mission the pilot will survive death. Fall into a chasm though, tough luck.