Sounds like a skill issue to me.
Any source — and there are numerous ones — of random legendaries into, say, Maestra into (‘The Amazing’) Reno — repeated by Tess, Zai or whatever as needed — would easily take care of your board… especially if you’ve run out of your free wins limit ( 
man, while writing that piece, I seemingly forgot the exact formulation or wording I was preparing for this post; ah, well, no matter, I guess…) — why, my ‘opponents’ would pull of such manoeuvres for twenty or so games in a row every day, then.
Truly skillful top-Legendâ„¢ playarghs should have no problem in playing like that, thus showing their skill, regularly and consistently.
PS Looks like your opponents couldn’t properly master such skill-intensive cards as Marin, Griftah, Zephrys and whatnot. As said, skill issue. 