Thinking like the energy blast when you revive. Maybe make a new shield where instead of blocking hits it has a nitrome-like blast with the pushback but with minimum damage. Of which the shield will be broken and can't be used until it's reformed. At that point you can use it if its in the red or orange states but the explosion will be smaller. Good? Bad? I'm just spouting out ideas hoping one will be good.

2* Reverser
___1* bomb damage but with 2* bomb radius ( going off the blast bomb line)

3*Saviour
Same specs as above but each star +1

4* Inhibitor
Same specs as above but each star +2

5* Last resort
Same specs as above but each star +3 plus starts with ctr low