AP & AD itemizations
WIth ADCs running rampant in every lane and sometimes even in jungle, and AP itemization in complete shambles this season, mages have been gutted and are rarely seen. Yes, Ahri, Leblanc, Orianna, Lux and Viktor are seen every now and then. Considering Ahri and Leblanc are part assassin, there are 3 mages that are kinda viable ever since seaosn 6 started.
Just have a look at playrates of champs- http://champion.gg/statistics/#?sortBy=general.playPercent&order=descend&roleSort=
Ap itemization is the primary reason for that. Costs have increased,
/
is a must,
being bad compared to
and 
's being the only item that couters AD.
AD champs have so many options to almost completely nulify mages

and
/
have made it impossible for not just mages, but even assassins to kill ADCs anymore
What's annoying is that ADCs can build
or
or
or

or slight variations of these. It's crazy how many options ADCs have. The problem right now is that
are not core ADC items. ADCs can go triple crit items and still melt tanks without last whisper items, while mages have a hard time killing tanks even if they have barely one or 2 MR items.
is a super core mage item. Every mage NEEDS to build it. Also,
is a joke of an item right now. So expensive and the stats are miserable. Needs a severe buff.
needs some love too, make it more viable to mages, not just a select few
too. Also, making
. Seeker's is so weak, especially cause it's passive is not permanent. When it transforms in to