If you go out of vision in any way shape or form you'll cancel Mord or Darius's ult from casting, however it'll go on cooldown for Mord or Darius even if it wasn't casted - Darius will need to be right before the blade hits to experience the bug, Mord's is consistent with Ezreal E'ing away or entering a bush.
If the target is still in range and targetable by the end of the duration they're banished together with Mordekaiser to the Death Realm for 7 seconds, during which they Suppression icon cannot leave.
IF the same works with every ability with a channel that can't be interrupted by conventional means like CC darius ult is just like cc
i think stasis is the only CC ability that stops channels of this type
