Played tutorial and a few rounds in the swamp
I'm not a card player, i know only the basics of yugi and magic, so my feedback will be pretty basic.
>looking for ideas on more content (battles)
my basic tip would be to use decks as characters, like magic. this dud don't have high level minions but tons of low level, so he will swarm you; this dude uses tons of magic cards to deal direct dmg; this other dude stalls and foce you to finish your deck and die(i dont suggest that because it's lame play and players will get mad at it) etc etc
Overall impression
Game works and i didnt see any bugs. My problem is just how generic it feels even for me that don't play this genre at all. if you are making this game for fun, i don't see any problem with it; if you wanna try to sell this, i don't see anything to make it stand out. You can't really match the polish and complexity of an heartstone, magic or yugi; so you need to give your players another reason to play.
Random thoughts i noted:
title in titlescreen is a bit blurry, i'm in 1080p
in the first intro video the white elf/goddess image has a cut on the left side, like it's two images 1px or so missaligned;
"+1 mana after each turn + refill" tutorial might be placed too late
music in the tutorial is maybe too upbeat since the game itslef it's not very fast-paced
once a minion atks it should have a "something" to remind you it already attacked this turn, the warning on click is fine;
"how to win" imo is also set very late in the tutorial
the "sleepy" Zzz.. on minions it's also blurry
in the main screen after the tutorial, with the knight statue: it dosent seem a plaza with a big statue in the center, but a miniature that you are seeing while stretched out on the ground, like a cat
i don't like to have the title of the game as a transition image. many changes are possible, imo use arts of your cards randomly (you could also have a setting to use your fav cards)
i don't like that the missions you accept don't have a visible "reward on complete". dunno if it's a design decision, or just something you still need to implement
i like map screen a lot.
dungeon gate used for transition is cool, but very blurry
gargoyle txt "everytime u pee" it's very funny, but it's not alligned to the overall tone of the game. Imo all your game should be wacky like that text, or all straight.
Moreover, since your game (imo) dosen't have an appeal on it's own, this could be a way to sell it better. However, since i don't play this genre i don't know if there is already a card game with LMAO guvenile humour.