Ymir 4444HP

10% CDR on Ymir isn't all that good either. No counter items, having Cloak of Meditation, Soul Gem, etc., makes this a difficult build to recommend.

That said, if you feel pen items are powerful right now, a tank has 2 potential directions they can use to counter that (to some degree). One would be a higher health focus rather than higher protections (e.g. item w/ prots + higher health vs just prots such as Mantle). Unfortunately high health can also be countered with items like Qin's Sais and Soul Reaver, and Qin's in particular is a meta ADC item right now. The other would be to go more bruiser and try to deal enough damage or support team damage to back off the damage dealers.

Manticore's Spikes fulfill both the first and second criteria to a degree (high health, decent prots, passive that is offensive in nature). Hide of the Urchin, while a solid tank item in general for the base stats, is probably not preferred over the need for the item slot to build counter or utility items. Soul Gem is definitely not that great with a lack of other offensive items...if you really wanted to go with an offensive utility item and wanted some similar stats (e.g. CDR, a bit of lifesteal which honestly isn't important for a tank), I would suggest Pythagorem's Piece for the offensive team potential it provides. That said, I would probably consider other alternatives as well, such as Ethereal Staff for the health steal. Finally, I would probably slot Pridwen somewhere in here, for the higher CDR and the health shield that should come in handy for a god whose ult makes them pretty vulnerable.