Can we talk tanky Cassiopeia?
MR and armor runes over AP and m pen, RoA and Rylai's for mp, ap, hp, and kiting. Seraph's embrace for obvious reasons. Scepter, chalice for MR, Frozen heart for armor and mana, zhonyas for ap and defense.
She has a 500% ap ratio on her E from 5 seconds of fighting and high base damage when spammed. Building her tanky allows her to get off her damage without exploding. You could even build her 100% tank and she would have higher damage than most off tanks. Building her glass canon makes it difficult to use her to her full potential because she has 0 burst damage but the best sustained damage in the game.
She can be built off tank or full tank and I believe both are better than glass cannon.
,
,
,
,
/
,
, 
+
/
depending on the enemy team. Spirit Visage won't be as good after her heal gets nerfed, though.