Am I Nuts?....Swain
Alright, so I was looking at swains numbers...And I decided to crunch them.
Q - 255 (+ 90% AP) W- 240 (+ 70% AP) E- 235 (+ 80% AP) + 20% Damage amp R- 90 (+ 20% AP) (lets assume you get 4 ravens off in this test, so 360(+80%AP)
Runes - red - 7.8 m.pen yellow - 72 hp Blues - 28 AP @ level 18 Quints - 1x 5.0AP 2x 4.26 Armor (8.5 armor)
Masteries 21/9/0 (Notably 3% dmg amp from Havoc, 12AP from offence line, 6% M.Pen)
(not even going to count, double edge sword, spell weaving, or executioner, which could potentially add in another 9.5% damage!!)
Build -

@ Level 18 :
1842 hp + 650
+ 300
= 2792 hp
1174 mana + 650
= 1824 mana
91 armor + 50
+ 2.5s Invuln = 141 armor
30 Magic Resist + 50
= 80 magic resist
AP = 80
+ 120
+ 50
+ 70
+70
+ 33 from Runes, + 12 from Masteries * 0.05AP from Masteries = 457 Ability Power
Spell Pen = 35%
+ 6% Masteries + 8 Flat from Runes + 15
+ 15
+ -20MR aura 
So we can plug this equation at 30, 50, and 100 MR and find Swains full burst! or X- 20 * 0.59 - 38
@ 30MR 30-20 * 0.59 - 38 = -32 (league only lets you go to 0, but abyssal brings you -20 reduction, so -20 for our purposes)
So Swains full burst is .8AP = 367 .9AP = 411 .7AP = 320 .2AP x 4 (.8AP) = 367
E = (235+.8AP) + Q =(255+.9AP) + W(240+.7AP) + R(360 + .8AP) = 2,555.
Okay, not so great for a full burst.
BUT.WE.FORGOT.SOME.THINGS.
Swains E, gives him +20% Damage Amplification, and we get 3% Damage amplification from our Havoc Mastery.
So its 2,555 + 23% Damage
BUT.WE.FORGOT.MORE.THINGS.
So looking at our target with 30MR, They already take 20% increased damage from us, do to our magic penetration.
So our formula is 2,555 * 1.43 (+20% pen + 20%E + 3% Havoc)
AND WE FORGOT MORE THINGS!!!!
We also have
! Which is 12% Current HP + 43%, makes it worth 17% Current Health over 3 seconds.
In closing, @ 30MR = 2,555 * 1.43 + 17% Current Health (3,654 damage + 17% Current HP over 3 Seconds.) @ 50MR = 2,555 * 1.43 + 17% Current Health (3,654 damage + 17% Current HP over 3 Seconds.) (We still reduce ALL of their MR) @100MR = 2,555 * .92 (+.23) = 2938 + 15% Current HP over 3 Seconds)
Hell even for 200MR = 2325 damage + 15% Current HP over 3 seconds
Is
that strong, or is my math way off? He does this damage, all while running around with 2792 hp ( shoot, + 36hp + 3%) 2912HP, 149 armor, and 80MR, Oh, and he heals with his ult...
Switch up void and spirit visage into deacap or abysal as needed.