Your top 3 mastery champions create one super-champion...
How OP is the result? I want to see if anyone can actually beat my monstrosity. For this thought experiment, please try not to change the nature of abilities for the sake of combining them. For an example of what I mean, see the explanation for my creation's W. You could just toss components of the abilities together piecemeal, which is the only way these 3's ultimates could come together into one, but that's cheating, which is why I only threw that ultimate idea out there as a for instance.

Autoattacks are ranged (Pix), can root (Staggering Blow), and apply a stack of Acquired Taste.
Q double-slows (Tongue Lash, Glitterlance), pulls you toward any enemy champion or monster hit, stunning the target (Dredge Line), and applies a stack of Acquired Taste (stunning if at 3 stacks).
W devours enemies/allies (Devour), shields you and causes your basic attacks to deal bonus magic damage (Titan's Wrath). Ally/enemy/self Whimsy would not apply, as you would no longer be able to W yourself, and its enemy/ally duration would end long before the enemy/ally exited you.
E either shields you (double shield) or an ally (Help, Pix!), creating a slowing triple explosion around person with said shield (Riptide) and popping your own (rapidly decaying) shield (Thick Skin), or it damages an enemy champion (Help, Pix!), likewise creating a slowing triple explosion around said champion and popping your own shield, on top of granting true site of that enemy for 4 seconds. Passively, it stores all damage taken as Grey Health, which you rapidly heal a portion of after taking no damage for 2.5 seconds.
Your ult passively gives your basic attacks and abilities bonus magic damage. When activated... well... I can't even think of a way these could be combined without tweaking them significantly, resulting in one of the most broken abilities in the game. You enlarge yourself, knocking up units around yourself for 0.75 seconds, gaining bonus health, and slowing nearby units for 7 seconds (Wild Growth). Then, after channeling for up to 15 seconds you teleport to a target location solo, or with an ally, after a 0.5 second delay (Abyssal Voyage). If enemy champions happen to be in the straight line of your voyage, they are hit by a depth charge and knocked up. See what I mean about having to just kinda play loose with the 3 ults to make combining them possible?
Even if you say only Tahm's passive can remain, as the rest cannot possibly function simultaneously, it's not like this champion isn't already the bane of every League player's existence.






...... O_O
NO ONE DIES


. Knock-up poison bomb trail? Rewinding slow shield? Shouty fling super-speed/slow? Undying super-mode charge? 'kay.


+
+
(Manamune before Arch Staff)

Mid-game:

I get so much healing
I'm too lazy to do this.