What is the Hollow Priest's SECRET OATH buff exactly?

In Lothric Castle the Hollow Priests cast a spell that looks like Sacred Oath. Is this simply a sacred oath or is it something else entirely! Let's find out! -------BONUS NOTES-------- Sacred Oath gives 10% more AR, Secret Oath gives 20% more AR. But combing the 2 provides 32.2% more AR. Since it works multiplicatively the more % damage boosters stack the better it gets! This is unlike defense where the absorption stacks diminishingly. So you can never reach 100%. Sacred Oath alone provides 10% absorption, Secret Oath/Sacreder Oath gives 30% absorption but when both used together only provides 37% absorption! In any case, this SECRET BUFF is core to getting both the MAXIMUM AR and the MAXIMUM ABSORPTION POSSIBLE! Music: Opening Move by Shane Ivers - https://www.silvermansound.com