For the mages I play (
), I look for their builds on champion.gg, they all build morello's instead of Luden's. I never see this in game, though. Is this meta or just a bug?
I rarely build Luden's anymore, the goal of a burst mage is to kill them with one rotation when you catch them with cc so you shouldn't need much cdr for most characters. The damage passive is nice but its better for poke characters, Morello's also gives nice damage and the grievous wounds passive is super relevant mid-late game.
If you are mostly using your shortest cd spell in lane and only using your cc spells to finish them off then you don't need the mana either, especially with Ahri, not so much with the others you listed.
Also, the health it gives you can help you survive enemy burst a lot as well.
I build Luden's on aram though for the mana gain on level from lost chapter XD
Also, cdr's effectiveness is mostly on long cd spells which you shouldn't be casting much. If your cc skills are off of cooldown your enemy has to respect it and play around it, but if you cast it even if you land it they will have a window of opportunity for a counterattack.
Edit: I would definitely go Luden's if you aren't confident with managing your mana on your character or are playing long range poke/siege type of strat.
because it is a terrible site which you should stop using lolalytics/u.gg and probuilds are all you need
that's just wrong,any burst mage build a 
item
U.GG is far more reliable
Sorry if I'm wrong I don't play mages, but don't they sell it mid-late game?
probably a bug
