You've made some incorrect statements about my build. I am taking spiritual retribution and both core 4s with my current build as shown in the picture here:
https://www.ddo.com/forums/showthrea...=1#post5665814
I am also using the lantern ring as I do on all my casting builds.
I am not taking either level 18 core obviously since I am 17 warlock / 3 paladin. If I went 18 warlock / 2 paladin the enlightened spirit core gives me feather falling, knockdown immunity and 3d6 more light damage on my eldritch blast. What I am getting from 3 paladin instead of 2 paladin is the defensive stance which gives me 25 PRR, 15 MRR, +3 more to saves and 20% more hitpoints.
Feather falling is lolz for a level 18 ability. Getting knocked down hasn't even been a minor problem with this build. As a percentage of damage output 3d6 as add-on damage isn't making that much of a difference compared to the extra PRR and MRR. Being more survivable also increases dps because you don't have to exit combat sa much to stay alive.
So to me the basic trade-off of /2 pal vs. /3 pal is 3d6 light damage vs. 25 PRR/15MRR/+3 saves/20%more hp.
There are no absolutes in this game when trade-offs are involved. If a person's biggest challenge of the new content is incoming damage 3 paladin may be a nice option for them. If there biggest problem is dps they can go with 3d6 light damage. On most fights 3d6 extra damage is a rounding error resulting in one more cast some times and 0 additional casts other times.
As for the critical damage % I didn't notice much of a dps loss when I changed builds, but being more surivivable also helps with dps because it requires less self-healing and allows me to stay in combat and fight continuously. I'll have to check that out - I always thought it was cumulative.
As you can see from the original build I was a pure 20 warlock and I was taking the tainted scholar capstone for extra critical damage. The build worked great for me everywhere but wasn't capable of soloing ee Amarath. After the changes I was able to solo ee Amarath so the trade-offs are beneficial in my opinion.