My gut reaction was no, but the more I think about this the more I like it.
There are a lot of mythics which have potential with guaranteed kills or other interesting mechanics but you can only pick a few because making the most of 16 slots is so important, so you have to balance team cost with 13-cost legendaries or things like Horrorclaw, Musashoid and Spookoid.
I think increased or unlimited team cost would open up more strategies without invalidating a lot of the established good UC monsters because so much of it comes down to how they work mechanically rather than things like their stats.
I think for PvP also sooner or later they have to remove cost limit because as monster collection grows the best edge they can give to p2w is by increasing team cost limit.as per the saying only constant is constant …Same for 206 let’s see when new number arrives
That may be possible to add extra 1 or 2 team cost upgrade as buff,or pretty cool thing is unlock 206 as default team cost by purchasing rather than normal way that’s way p2w has able to enjoy game at early stages without affecting game logic and not unfare towards f2p
