Is the low cooldown on Lux ult justified when compared to Xerath and Ziggs ult?
In the world of artillery mages, I feel like Lux is King( or Queen), because her ult is very spammable, syncs the rest of her kit, and it is just generally a very reliable good execute ability. She even gets a cooldown refund of 50% on champ kills making it possible to get the ult down to 15 sec with max cd.
Xerath on the other hand ult does the most damage, but is very unreliable and does not really sync that well with the rest of his kit. it kinda works all on its own. Ziggs ult does about the same damage as Lux, has about the same amount of counter play depending on how far he ults, but has a huge CD.
I get the Xerath and ziggs have more spammable none ult spells, but they don't seem to justify the huge gap in cooldown that Lux gets.
So, my question is, is the low cooldown on Lux ult justified when compared to Xerath and Ziggs? Should Xerath and Ziggs get lower cooldown on their ults?