Riot: Fixing Quinn bug=add another bug(ON PURPOSE)
So before last patch there was a bug that forced
into permanent valor form by activating
at the very end of her ult.
So rather than fix whatever was going on under the hood to cause this weird interaction, someone on the patch team decided to be lazy and simply made it so Quinn can't use tiamat's or hydra's activate for the last second of her ult. Which is terrible for 2 reasons.
The last second of valor form can be surprisingly important. It's when you can time in a quick burst of damage and let skystrike finish off your target without having to worry about pressing R. Not being able to use hydra's activate during this time mean's if you want to assassinate someone you're losing a lot of burst damage.
But the real issue is this is just bad game design. You don't solve a problem by creating a slightly less noticeable problem. Additionally Riot never even released in the patched notes someone like: "Fixed a bug on Quinn... she can no longer use tiamat during the end of her ult." It's rather unprofessional.