User blog comment:Lykrast/CCC5 - Morma the craftsman/@comment-5686533-20140905143109/@comment-1330314-20140910044742

Plastron of Immortality isn't exactly the "pure tankiness" option, considering it also gives AP, mana and mana regeneration. Trimming the stats down to MR and a bit of health (and perhaps some sustain-based stat) would clarify the Plastron's role as Morma's MR option.

Similarly, Plastron of Dominance builds from a Frozen Mallet, which is the source of the item's problems: it gives the Plastron AD Morma doesn't need, on top of a perma-slow that starts out as a weaker version of both Frozen Mallet and Warden's Mail's passives. You could potentially have much stronger and much healthier CC on this item.

The scaling to Sprint's shield is a little weird. Granted, you want Morma to scale well with resistances, but you already have four other resistance scalings in your kit. It might be a better idea here to give the shield a health scaling instead, so that you don't skew Morma's build options by forcing him to build pure resistances.