If you going to continue talking about swain in each new post, I would suggest you rework ability's and fix the problems you see in his new kit. Completely redoing abilitys in said kit is fine, Replace X with Y etc.
If you want to talk about a Drain tank Diver kit, I would sugguest you create from scratch a new champion and post it in creations and concepts.
You got to realize that all your buffs stacked is a bit to much, it overloads his kit. E alone is providing 1/5 less burst if used on the right target, that's pretty huge especially on a sustain tank. your adding in AOE, but not nerfing damage. AOE tends to be lower damage and for good reason.
Lets look a little closer at swains old R. level 1. 50 damage a second, hits targets max 1 time per second, checks for targets every 0.2 heals for everything hit. so you can hit a total of 25 targets per second healing off all of them. 3 seconds of R, even vs just enemy champions is 150 damage with 60% ap scaling. 300 for 6 seconds, 120% ap scaling. lets say 4 seconds, a reasonable amount of up time in a fight. 200 damage, 80% ap scaling a gain of 80 hp with 48%ap scaling. Assuming you hit all 5 targets that's 1000 damage with 400% ap scaling, 400hp and 240%scaling.
When talking about balance AOE needs to be balanced around its best case not being to easy to land or to strong.
Also just point out that his ultimate could put out at level 1 1250 damage per second with 500% ap scaling in the very** unlikely and rare** moments he had 25 individual targets.