An idea to replace Strength of the Ages

Strength of the Ages adds maximum health up to 300 and heals from nearby large creeps after reaching its cap. (Soon to be 6% HP in the 6.1 patch)

It seems like it's designed to scale with health stackers, but Grasp of the Undying fulfills that role much better. So instead of looking to give a health steroid, I propose something that could focus on champions that build resistances.

Shroud of the Soul: Lv∙0.9 (+5% AR) (+5% MR) shielding per second for a maximum shielding of Lv∙13.5 (+75% AR) (+75% MR) at 15 seconds.

Inspired by the ancient Runic Blessing, getting a shield before the fight helps counteract burst and harass, and since you obtain shielding every second, it's still going to assist throughout the fight. At Lv 1, you get just enough to block 2 auto attacks and/or most of the minion harass that can come your way. At Lv 18, you should have enough to take on plenty of hits from an ADC or a few major spells from a mage. Compared to Grasp of the Undying, this keystone won't deal any damage, but it makes up for that with pure defensive power in the exponential scaling for resistances. Since it's not considered healing or health, it'll be unaffected by grievous wounds and % HP damage, and also any personal health scaling.

Comments? I'm still very worried about how well the shielding actually scales. If it seems too little or too much, let me know.