The new Bond of Stone just makes so much sense to be paired with 45% CDR, or make a 4th keystone that is slightly different to the new Bond of Stone and you have a Bond of Stone that scales with health and another that is more utility based. I will give an example idea:
**A 4th utility keystone ["cunning"]:**
Your crowd control against enemy champions restore 5% missing mana for yourself. Your hard crowd control against enemy champions heals the most wounded nearby ally champion for +10 per target's level (+20%AP) health.
_(So the self passive is all crowd control, including the softest like slows, where as the support effect is only hard crowd control so the effect won't have a cooldown since hard crowd control is already linked to decent to longer cooldowns. This is an option for crowd control mages or mana hungry tanks can take within the support role and gain access to 45% CDR - where as the new Bond of Stone is for the pure CC hard-tank supports that grant a potential much higher healing rate for all of their allies and makes themselves tankier.)_
Just really want the option for the CC mages can have a support keystone for themselves that don't get shields or heals themselves, since Thunderlord's Decree technically is not a support keystone at all.