Mordekaiser needs his builds to be more distinct

Currently Mordekaiser is powerhouse from a durability perspective and damage perspective. While doing great damage is fine, being invincible while doing it is a problem that needs to be addressed. The problem that makes Mordekaiser seem invincible (in my experience playing him) is his W_ Indestructible_ (lol ironic name):

Indestructible

Passive: Mordekaiser stores 30% of damage he deals and 15% of damage he takes, reduced by 75% against non-champion sources, as Potential Shield on his secondary resource bar, up to 30% of his maximum health. The Potential Shield bar has a minimum of 5% of his maximum health.

Active - First Cast: Mordekaiser consumes all his current Potential Shield to himself for 4 seconds for the same amount. At start the shield decays very slowly but exponentially increases near the end. After 0.25 seconds he can re-cast the ability.

Active - Second Cast: Mordekaiser consumes the remaining shield, Heal power healing for a percentage of the amount.

The problem with this ability is it only scales off 30% of his max hp, Mordekaiser will build HP regardless of his build thus, why he feels invincible all the time. We need to "unhook" this ability's innate scaling off his max hp and instead force players to commit towards hp heavy build, damage heavy build, or hybrid. The method is simple:

Indestructible

Passive: Mordekaiser stores 30% of damage he deals and 15% of damage he takes, reduced by 75% against non-champion sources, as Potential Shield on his secondary resource bar, up to 60/120/180/240/300 (+20% of bonus health) shield value.

Active - First Cast: Mordekaiser consumes all his current Potential Shield to himself for 4 seconds for the same amount. At start the shield decays very slowly but exponentially increases near the end. After 0.25 seconds he can re-cast the ability.

Active - Second Cast: Mordekaiser consumes the remaining shield, Heal power healing for a percentage of the amount.

So the major change to his W here is it now has a base value meaning he'll always get a shield, but the ranks you put in it matter. Furthermore, it scales off 20% of bonus hp, the reason its so low is because Mordekaiser already naturally builds hp regardless meaning that a stronger ratio would make the shield too powerful. Shields are not meant to make you unkillable, instead they provide a buffer of hp to absorb incoming damage, but it doesn't last forever. Mordekaiser's shield last a long time so its value needs to nerfed so he can't use as crutch to withstand huge amount of burst. If a Mordkaiser starts a fight at 25% hp vs. someone at full and pops his W, he should not be able to tank all their damage and kill inside the shield's duration, that is just wrong.

**TEST 1 of his new shield scaling (standard build, considered Hybrid): ** rank 5 (300 base value), items built: (+300 hp), (+300 hp), (+80 hp).

pop W at full charge: 300+ (bonus hp total (680) x 0.20) = 436 shield.

TEST 2 of new shield scaling (tank buuld, less damage more hp) rank 5 (300 base value), items build: (+450 hp), (+300 hp), (+425 hp)

pop W at full charge: 300+ (bonus hp total (1175) x 0.20) = 535 shield.

As you can see, his tankier build would have a better shield (and also resistances to back it up), this would make it strong on a durable Mordekaiser, but less powerful Mordekaiser on a damage-focused Mordekaiser. The numbers I used is only from 3 items, and the disparity between the 2 build will only grow the later on the matches last. This change I think will help make Mordekaiser easier to handle and also lay the groundwork for an easier time to balance him in the future. Thoughts? Comments?