It still does not answer the question, how is it possible to open mine on first click with hawk eye.
In your case, there's at least one bug, which explodes not only mines, but any number cell around. This number cells does not spread activation, but counts as damage. As a result, by exploding 7 (61 то 54) bombs i'm getting whooping -22 hit on 3rd level with 10hp at max...
And, yeah, chain reaction should be less destructive. 3*3 damage is overkill. Even activating 3*3 zone around mine is quite painful. I guess, some boss modifier combinations should have more value than each of them apart.