So I tried this game, it seems pretty fun so far. I can't figure out how to get tooltips to show up in the inventory yet, but otherwise it's fairly intuitive. Funny enough I used all the cash money gems you get through the first missions and got this amazing legendary (Dracula) and steamrolled a bunch of people, until I realized the problem with him was he was too sustainable: he gives 2 hp to every unit you have out which if you play right makes you obscene. Someone was able to beat me by rushing a soldier past my line and immobilizing the dude I summoned to stop him and he just moved the soldier up and he finished me off. So there's definitely way more depth to strategy and I had to pause to reflect on the lesson and rebuild my squad.
That said, this feels very pay-to-win (maybe pay-to-compete) as I saw some utterly broken legendary dudes in the unranked pvp. It was kind of frustrating after a while. The legendaries are where the real gameplay and deckbuilding is and those are not super common.
If I had one complaint, though, it is the cash money to green gem rate in this game. It's pretty obscene, it's like $2.50-$2.00 PER UNIT CARD which is insane. I'm not sure how much of these green gems you get later on so maybe it is totally a luxury, but while I would normally drop a few dollars on any mobile game that's fun to play for a bit just to support the devs and such I don't think so with this one. It feels like '$50 season pass lulz' level of player-gouging.