Gungans in Territory Wars mechanics

Our guild is facing a Gungan team in TW that has a Boss Nass datacron - extra health/pro at lvl 3, increased TM at lvl 6, and basically a revived plasma shield at lvl 9. So far, it is impossible to beat. May be the hardest team I have ever seen in any facet of SWGOH...crazy amount of turns, no damage taken whatsoever, and match goes to a draw every time.

However, my question is about mechanics. Gungan kits are wordy, so maybe I'm missing something but..

1. why does the plasma shield continue to gain 1 stack every once and a while? 
2. why does the plasma deflect certain attacks?

In my match, plasma shield would be down to 6 then suddenly be at 7 or start at 10 then suddenly be up to 11. Also, shield deflected at least 30% of attacks from my non-GL toons. At one point it deflected 4 attacks in a row.

Thanks for any advice.