So let's talk about the Mole Master's new lair. This is the sort of lair that most supervillains won't create, but he's got earth manipulation powers and has options many villains don't.
Mole Master tapped into some geothermal vents and is using a binary cycle power plant to drive energy for the base. His control over magma flows made setting this up easy, and he reports that the theft of the power plant itself went off without a hitch. Congratulations!
The efficiency of this type of generator is about 12%, That sounds low, but nuclear plants for years operated at numbers like 5%. MM also informs me that he's rigged the system to vent lava into the base as a last-ditch mechanism in case of invasion.
Water is distributed through the base using a gravity pump. Water purification isn't an issue for him right now as the base is situated below the water table and he's just draining off that for now.
He installed a back-flow prevention system to account for flooding, and there's several sub-caverns and weakened floors that are strong enough to support foot traffic but will give way to reveal emergency reservoirs if a large enough mass of water comes down on them.
The air purification system is only for the holding cells that MM installed. They're run from the geothermal power plant. I'm not 100% sure of the terminology here, but I did some searches. Mole Master says they're "venturi scrubbers", or wet scrubbers, that supplement the ventilation fans that keep air blowing through the complex.
Mole Master is using the CO2-laden atmosphere in the rest of the area as a supplemental security system, since he doesn't personally need to breathe.
The biggest expense in the lab is the circulation system. Mole Master reports that the scrubber mechanism will suffer from wear and abrasion and must be replaced. The rest of the system is good for 2-5 years, with period maintenance and checkups. Fortunately Mole Master knows enough mechanics and engineering to do the basic stuff, and he's got a gang of guys who'll take cash under the table to work on the base for him.
Overall this is a mid- to high-level villain base, well situated and well defended (you'll note that I omitted any details about his security system besides the obvious - this is intentional). Kudos to Mole Master for a base worthy of a veteran villain!