Some of the bees have a large area effect. Breed that into a bee with a fun trait like end, creeper or the like, and place it under his house/spawn and encase it with the thaumcraft blocks. make sure to have the required bee traits like nocturnal, cave and rock for flowers. (don't forget to automate it so the bees will continually spawn and be active.
throw 3 chocolate frames in the apiary to kill the bees off quickly, then remove the frames and leave the bees in the output slot. use wireless redstone to then turn on the engine and return the bees to the hive to enable their effect on the OP. Thus it is already in place, the admin may not find it right away, and you can activate it remotely when you are ready to do so.
With the large range bee, you could have it quite far away, and still hit him in his base.. seemingly from nowhere.
of course, the admin could be a member of the forum and ready about all the nasty surprises you have in store for him.