"The way this works is that when the proc happens (which is a 10% chance whenever a hot or direct spell heals, with a 45 sec internal cooldown) you gain a buff (the Blessing) on yourself. Now all of your heals for the next 15 sec cause an 8 sec damage shield. The shield stacks with itself. It includes healing done by subsequent ticks of existing hots on the target. Note that the spell has to actually heal, so hots ticking on a fully-healed target cannot cause the proc. However the shield is based on the size of the heal itself, not the amount healed – i.e. 100% overhealing will not proc the Blessing on the healer, but the shield itself includes overhealing once the Blessing is active. The shield can grow to a maximum size of 20,000 damage absorbed."
Which, in simple terms, breaks down into two parts.
1. Getting the buff
Any of your heals, HoTs or otherwise, that does healing (not 100% overheal) has a 10% chance to proc the Blessing of the Ancient Kings buff on the healer.
2. Putting up the shield
Once you have the Blessing of the Anicent Kings, your heals will grant your target a shield lasting 8 seconds that will have the damage absorbtion of 15% of you heals (including overheal). creates a shield around your target.
While the 45 second cooldown is a bit of a letdown after what Matticus was expecting , I am still really happy with the proc and its explantion. Part of this is because the mace becomes most useful to Paladins based on this explanation, which I will go into in a later post.