I like the mechanics of this a lot, they have a lot of potential! Very creative interpretation of the theme. Having a full tutorial that guides you through one mechanic at a time is really impressive for a game jam entry, and the polish on the menu shows how much effort went into this as well. I like the little paper doll style of the characters.
I played to the end - the game can be quite hard, but it was pretty fun once I got a feel for the strategies. In terms of suggestions maybe nodes could drop their connections automatically when you drag a new one in so it's easier to quickly switch strategies, and the countdown at the start of each level could be a little longer to get things set up. I felt like it might also help to have icons on each of Attack, Magic, Heal and Defend as reminders of the conditions they trigger in (like symbols for high health and low mana on Attack for example).
Very nice idea overall!