Trinity Force is a strange item. It's a jack-of-all-trades item that gives average, even mediocre stats, all across the board, although the % boosts are nothing to scoff at (12% movespeed, 15% crit chance and 30% attack speed). It gives 30 extra AD and AP, 250 HP and mana, and it has a slow chance (1 in 4) for on-hit effect appliers and basic attacks, as well as...

The upgraded Sheen proc.

Trinity Force applies an extra 150% of the holder's base damage onto the holder's next basic attack/on-hit applier. This means that no matter how much AD you stack, once you hit level 18 Trinity Force will not be doing much damage at all. I do know that on Skarner, Gangplank, Nasus, and Ezreal it's most certainly not a bad item; however, once level 18 comes around Trinity Force in this respect has slammed into a ceiling.

This is why I am advocating the change of Trinity Force's passive, so that it will scale in a Lich Bane esque fashion; in the case of Lich Bane, it will not lose potency unless the user stops building AP; in this case, it should scale off AD, obviously.

In other words, instead of applying an extra 150% of the base holder's base AD Trinity Force should apply an extra 80-100% of the user's total AD. This will completely leave users of Trinity Force unchanged in mechanics; Nasus will still have most of his damage coming from the Qstick getting farmed, Skarner gets nothing more than some incentive to build slightly more AD (since in his case his output might fall unless he builds Trinity and a Gunblade) and Talon will still remain an AD caster. However, Ezreal, Gangplank, and other users of Trinity Force who build AD beyond Trinity Force regularly will be buffed instead of having the damage from Trinity cap at 18.

By doing this you basically make it a guaranteed crit. I believe it's fine with base AD,.considering most champs at 18 have around 100 AD, 150 extra damage is a lot of damage if you're able to proc it well

1) Everyone caps at level 18... that's where it stops.
2) Trinity Force specifically caters to Tanky-DPS, occasionally bought by some AD Carries for utility+poke/burst. Tanky-DPS are intentionally designed to scale with levels harder than AD Carries, by shifting the scaling of Trinity Force from primarily levels to gold, your making itemization choices generic and hazy. Everyone AD would have to buy a Trinity Force, regardless of role, and everyone would then become influenced by its Tanky-DPS origins and utility.

If it applied total AD it would by far become the most dangerous AD item in the game.

As it stands. most champions building glass cannon work better off of just building flat AD over triforce. Triforce is mostly a tanky-dps/tank item.

I can already build Talon to kill targets in one hit with Q without using triforce. If it was modified this way, AD casters/on hit characters like Ezreal would become immensely OP.

I would be happier if it granted 100% increase based on physical plus 50% based on AP, it's set up as a hybrid item but in actuality, the AD, AS, crit, and both procs improve around physical damage aspects, I did not know Triforce proc only base AD... But either way, 50% AP + 100% damage would be better for most.

Trinity Force is one of the few items in the games that i would say doesn't need to change, It works really good on some champs and its ok on others. and for everyone else, there's lich bane

It doesn't fix anything. Full AD carries will nuke too hard, and Tanky-DPS will just become even more OP than it is now. Atma's is/was the OP part of Tanky-DPS, not Triforce. I had a reverse Atma's item in mind which just gave a huge amount of AD/crit chance which got reduced with bonus HP so that the glass cannon would gain viability, and even that got denied by quite a few people.

Protip: Phantom Dancer + triforce = Boots 2. No need for boots and you gain more damage and survivability.

This item would become much better than an IE. +400 damage on next attack versus maybe a difference of 200. You also gain all of the utility benefits such as movespeed/slow chance on top of increased HP/MP/crit chance/attack speed before even considering the proc.

Not hard to reach 400-500 AD max farmed. If you think games consisting of incredibly good players last anything less than 40 mins, you've got absolutely no idea what you're talking about. One-shotting rarely happens. Killing people in three hits, though, is almost every other game. That's not pubstomping -- it's called being good and demonstrating that AD carries don't need this buff. If the opposing side is counter-building so well that the normal AD carry will be incapable of getting fed or dealing damage, they will lack AD, and thus will not scale on the buffed triforce as well as they should be anyways. If people counter-build, switch lanes or start building armor penetration like heavy AD nukes should be to begin with.

This effectively makes a base hit after skilling deal 1k damage, without a crit. IE makes this 1250 + 500. 1750 damage on a single skill, and base hits which will range from dealing 500-1250 damage each. Obviously I'm neglecting armor here, but if triforce was buffed this way, it still would cause an immense boost to damage outputs to the point of making AD casters better nukes than AP casters.

AD Ezreal would become OP with this. His Q has what, a four second cooldown, incredibly long range, low mana cost, which scales 1:1 with AD, grants bonus attack speed when it hits, and applies triforce procs and on-hit effects like chance to slow. How ISN'T this item change OP on Ezreal?