The closest precedents I can think of to apply to point 2 of Emissary of Redemption are the ruling for how Arcane Ward interacts with concentration and Warding Bond. I will admit these are tenuous, and if I can think of a more direct comparison, I will edit it in.
If the Arcane Ward has 45 hit points and a creature deals 50 damage, the concentration check is based on the 5 damage (DC 10) that makes it past the ward instead of the 50 damage (DC 25) the attack dealt.
Warding Bond grants resistance to all damage to the target. The caster takes damage based on the result of the resisted damage. (Any resistance the caster has can apply to the damage transferred to the caster.) Otherwise, this spell would cause 150% increased damage, just split between two targets.
I think these rulings would imply Emissary of Resistance point 2 is half of the end result to stay consistent with other rulings.
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Monster Slayer is probably the best attempt I've seen at making Hunter's Mark less mandatory and actually develops a ranger's monster knowledge niche into something useful.
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Drunken Technique makes it a bit less painful to skip Mobile. Drunkard's Luck combines really well with Diamond Soul iirc, since I believe granting yourself advantage with Drunkard's Luck would also apply advantage to rerolls performed with Diamond Soul if Drunkard's Luck isn't lucky enough the first time.
