Thanks for playing and for the feedback! I actually played Onward Blocks during the GMTK jam, I totally get that comparison! Yeah I completely forgot to give some player feedback for the switch in-game. I totally get your confusion over the immediate action button, however, the actual purpose for it is to get actions off last minute (before your opponent). This allows you to block just before being attacked, or get off a second block (thus gaining a Deflect) to quickly deflect a fire attack.
Thanks again for playing! :)