If you’re currently not in the position to land hard hits against them because of their shieldings you’ll have to weaken the enemies defenses and stall their next steps. If they are not able to act or to re-organize their steps they are vulnerable.
Something along the lines of this:
For example Great President Malphas or King Vine (both are experts at building and destroying defenses)
You could try to go over the “return to sender” route with the existing link (if you type “return to sender” into the search bar you will come up with a lot of tried and tested approaches)