Ult should refresh if it doesnt kill target. That way he can keep trying until it suceeds.

True Noxian determination.

Killing the target makes it go on CD as Darius is now content that he got his kill.

Just make his ult no cooldown ever, one-hits anything he dunks(including minions and neutral camps/baron/dragon) and then everybody will stop crying...
And just uninstall :|

The easiest way to fix Darius is to remove the ult refresh. Or remove the passive.stacks after he dunks. He builds super tank so melting him is nigh impossible (remember the fact that their are other champs in the fight who might deserve some attention, making darius the target allowing others to capitolize on not being touched) and he just waits till he can dunk three times and call it a day. In a fight where it can be fought down to double digits in hp every time, which is nearly every single fight, darius makes that impossible. Having a darius on the team changes the ENTIRE game format but only.for the enemy team. This is the unfair advantage. A single champ shouldnt be so disruptive, a comp sure! But one guy? Come now...