New executioner's calling will cost 800 gold, and applies grevious wounds for 3 seconds on every hit. Not the hits below a certain % of health, just every single hit. And the item it upgrades into not only gives APen, it applies the wounds for 5 seconds instead.
So now any time that you want to play a sustain champ (Mundo, Vlad, Warwick, Aattrox, etc) don't, because it costs exactly 800 gold and 1 auto attack to render you almost completely useless. They removed the original executioner's calling because it didn't have enough counterplay for sustain champions. Apparently making it apply on every auto instead of just one's below 40% health gives it enough counterplay to completely destroy sustain tanks.
Ah, well, back to playing ADCS for literally every role.