a expensive way of killing him:
add a room to your base with a matterfabricator. the matterfabricator should sit in the center of the room, supplied with it's own MFSU. the walls should be made of warded stone (or reinforced tungstensteeliridiumwhatever-blocks). and the roof should be made out of something standard with at least one sticky piston to open the roof.
you should also have a hidden escape teleporter or a portalgun. if you're using the teleporter, then set a small repeater for the signal for the roof piston. the portal guns other portal should lead to a pressure plate. in both cases, automate the trigger for the roof piston...
and now it needs to rain, you show him your base, and that you have a matter fabricator. enter the room with him, use the teleporter and the matterfabricator explodes, strong enough to eat up even a fully charged quantum suit.