Improving Tooltip clarity – establishing a set of “rules” follow to reduce confusion.

There are many tooltips in the game that follow different standards of implementation, terminology, and some obscure information, while others display it proudly.

One of the big examples of this is seen in damage bonuses and damage increases

When a talent or ability can deal a second instance of damage(such as in the case of Giant Killer, Thralls's Alpha Wolf, or Maiev's Blade Dance), then the term "xx bonus damage" should be used, so Giant Killer would actually be unchanged, but Thrall's Alpha Wolf and Blade Dance would be changed to say they deal bonus damage, rather than additional in the case of Alpha Wolf and just generic physical damage in the case of Blade Dance. This is something that is already mostly in place, but it's good to set a standard for it. The key word here is bonus.

When a talent or ability increases or reduces the damage that something already does by a flat number(such as in the case of Illidan's Unending Hatred, Varian's Lion's Maw or Hanzo's Target Practice), the term "xx additional damage" or "xx more damage" should be used. In the case of a reduced damage, the term "xx less damage" should be used. Other variants could be "an additional xx damage", the key words are additional, more and less.

When a talent or ability increases or reduces the damage in an additive format(Such as the case for Medivh's Arcane Charge, Whitemane's Judgment Day or Illidan's Sweeping Strikes), the term "damage dealt by Y is increased by xx%", and when something is meant to amplify or replace this damage bonus(as is the case for Illidan's Battered Assault or Samuro's Crushing Blows), then use the terminology "increase the bonus damage provided by Y to xx%", in the case of a reduction, then "damage dealt by Y is reduced by xx%", or "reduce the bonus damage from Y to xx%". The key words are increase and reduce.
When a talent or ability increases or reduces the damage in a multiplicative format(Such as in the case of Sgt. Hammer's Splash Damage, D.Va's Defense Matrix and Ablative Armor, or Samuro's Harsh Winds), the term "deals xx% more damage" be used when the damage is increased, and the term "deals xx% less damage" in the case of a reduction. for things that modify these bonuses, "reduce the damage reduction from Y to xx%", "increase the damage reduction from Y to xx%", "increase the damage bonus from Y to xx%", and "reduce the damage bonus from Y to xx%", but I'm pretty certain the only instance of this happening is Sgt. Hammers Advanced Artillery, so it woulds say "Reduce the damage reduction from Siege Mode's splash damage to 50%, and increase its splash radius by 25%.". The key words here are more and less(the same as the flat bonus, because these are functionally having the same result, it's okay to overlap)

<>: Damage dealt by Living Bombs created from spread is increased by 35%. This is a more complete rewrite to clear up potential confusion for when Living Bomb deals increased damage
<>: Channel a defensive field in the target direction for 3 seconds, causing enemy Heroes in the area to deal 75% less damage. The Mech may move while channelling, but cannot turn. Damage dealt to the Mech from enemies within Defense Matrix still grants the same amount of Self-Destruct Charge. One way this could be improved is on the wording for the Self-Destruct charge gained, something like "Defense Matrix does not reduce the amount of Self-Destruct Charge gained from taking damage"
<>: Noxious Blossom deals an additional 160 damage to enemies afflicted by Nature's Toxin. Damage dealt by Noxious Blossom is increased by 25% against an enemy with 3 stacks of Nature's Toxin. This is an example of a tooltip that is downright misleading, as the initial damage bonus is multiplicative, but the extra 25% is worded as increasing the 100% more to 150% increased
<>: Increases Baelog's splash damage against non-Heroes by 100%. The initial damage bonus is multiplicative, and it should also probably be reworded to something like "Baleog's Basic Attacks splash in an area behind his attack target. Enemies hit by the splash take 50% less damage."

Now, next up, this is something that I'm going to directly link to a great post by /u/Veliaphus, which you can see here. In this, they go into some amazing ideas, like colour-coding abilities to help things pop out more, standardisation of the several terms across quest tooltips, and just all around general improvements that make tooltips easier to read.

Lastly, Shields. The tooltip consistency here isn't too big of a deal, as a shield is a shield, but it's still something worth pointing out.

There's no consistency here, some use "grants a X point Shield for Y seconds", while some use "grant Z a Shield that absorbs X damage for Y seconds", and then there's "Z gains a X Shield for Y seconds". What I propose is to use the terminology "Gain a shield that absorbs up to X damage for Y seconds" for flat shields, and "Gain a shield that absorbs damage equal to XXX% of Z for Y seconds"

<>: After taking damage while below 75% Health, Artanis gains a Shield that absorbs up to X damage for Y seconds. Basic Attacks lower the cooldown of Shield Overload by 4 seconds.
<>: Anub'arak gains a Shield that grants 40 Spell Armor and absorbs up to X damage for Y seconds.
<>: Hitting an enemy Hero with Chomp grants Orphea maximum Chaos and she gains a Shield that absorbs up to X damage for Y seconds.
<>: Pulling an enemy Hero with Chains of Kel'Thuzad causes Kel'Thuzad to gain a Shield that absorbs up to X damage, This shield can be gained 2 times at once. Additionally, Chains of Kel'Thuzad deals up to 270 bonus damage to Heroes' Shields.
<>: When Deflect ends, Genji gains a Shield that absorbs damage equal to XXX% of the damage blocked by Deflect for Y seconds.
<>: Xul gains a Shield that absorbs damage equal to XXX% of Xul's maximum Health for Y seconds.