When I’ve been using Boldur, his axe has been disappearing whenever I use Axe Throw while the rune from his ultimate is active. This seems counter-intuitive and seems to go directly against the intent of some of his other helix upgrades, such as the one which causes his axe to rebound back to him on a direct hit, or the one that gives him bonuses for retrieving his axe.
Having to wait for Axe Toss or his ult to come off of CD to get his axe back is unsatisfying, and nowhere near as fun as landing a direct shot and having it come back to you, or even just moving to pick it up where it lays. So I really hope this gets fixed soon.