In v4 I've found a few glitches and unintended interactions.
1. The combo ability counts when you click on a card rather than when you use it. So if you have an open card of each type you can gain infinite energy.
2. You can mash E to trigger end turn affects like the fortify on end turn or to clear out doom stacks on yourself (by eating them all at once). Mostly it's stacking fortify if you get the power to do so and making the game trivial.
3. The ability that gives you bonus attack and defense if you have starter or basic abilities isn't counting some ability as basic. Whenever I get it I only have 2 stacks even if all 9 abilities are basic/starter, and I don't know which one isn't counting.