What a game. You'd hardly tell this was made in SRPG Studio and certainly highlights the power of the engine.
The way you summon units was clever and very neat, and the idea of there being a whole host of features and things you could do that all depended on the luck of the draw felt exhilarating. Unfortunately, the whole 'luck' part was absent, as everyone's decks were predetermined. This made it less of a versatile feature of the game and more like a puzzle you had to solve. A puzzle wherein you didn't know where all your pieces were or what they did. It was aggravating in the first battle as there were a whole host of mechanics I had to trial and error into. A short tutorial battle before that one would have made it a lot less of a blind mess. The first battle also felt a lot tougher than the second, as the first you just could not brute force unlike the second if you played your cards right. Heh.
But I don't think I could comment without bringing up the game's aesthetic charm, which you nailed handily. It goes so well with the theme of card playing that it really sold the package. The map, the backgrounds, the units, the UI, down to the font you used, indeed, all wrapped up the mechanics in such a coherent way that it felt natural to just behold. The visual design you chose absolutely set it apart from the rest.
The system itself, I feel, could be pushed much further, but that might not be suitable for a quick jam entry. If this idea ever gets explored, I would like to be one of the first to see it, because it definitely pushes the envelope on what you can do with SRPG Studio.