Thank you so much for playing AND for the really in-depth feedback! It's really nice to see how people do their builds. I didn't expect anyone to use cards for extra dashes, but there you were!
A more thorough tutorial or guide would be quite helpful for a game like ours. We just really didn't have the time, with this being a one-month jam. To answer your questions though, duration modifies how long traps last—which include blazes (DPS pools), mucus (slowing pools), blisters (green mines), and mists (DPS smoke)—as well as the HP of minions—which include cultists, skeletons, graves, etc., as well as the hellgate, which is unique in that though it has HP, it cannot receive damage but instead deals damage to itself. All the other minions are destructible, but keep in mind the distinction between them and traps—blisters are traps and cannot be destroyed.
Since bosses always deal 1 heart of damage to the player, their damage only affects the player's minions. We know that that doesn't really feel the most intuitive, but we had to work with it. We'll definitely rethink and refine this if we decide to publish the game.
You brought up how the first bosses are really hard and the first few cards/artifacts really boost the player's survival rate. THIS was the very balancing problem wetried so hard to deal with but couldn't quite perfect due to lack of time for playtesting.
The exchanging mechanic was definitely intentionally forced, and I'm glad you got the reason why!
Lastly, we do admit that the butcher is our most difficult boss. If you watch our gameplay video, we actually lost to him too lol. We'll see what we can do!
Thanks again, and we're really glad you enjoyed playing!