New Dark Troop Idea: Miner

So, I saw the idea for a troop that would tunnel under walls (or something of the nature) but no stats were posted with it, so I'm going to post basically the same idea (pardon me for doing this), but with stats.

The stats would be as follows:

Cost: 250 Dark Elixir
Hit Points: 29 (same as level 3 wall breaker)
Movement Speed: (same as level 1 wall breaker)
Attack Speed: (same as wall breaker)
Damage Per Second: 90 (x2 against enclosed splash defenses nearest to walls)
Army Camp Space: 15
Preferred Target: Splash Defenses

The basic premise of this hypothetical dark unit would be that it tunnels under the walls of a base and zeroes in on the nearest enclosed Splash Defenses (Mortars, Wizard Towers) in a village. The unit would only be able to tunnel through one layer of walls at a time. It has the DPS of a level 3 Wizard but has very low health and takes up a good amount of space in the army camp to compensate for the increase in damage to Splash Defenses
Thoughts? Has this idea been suggested before? Is it totally OP?