Skarner is broken.

It's a fucking bruiser item, it's supposed to allow tanks to do damage. You are just salty, Skarner couldn't be OP if he tried.

Please note that trinity force can be searched using the words "tons of damage"- which may be a pun but is actually true. Not to mention champions that have a low cd ability can spam the proc on tri force (and along with the other bonuses too if they get the chance)... also hecarim can also do this (better might i add) and so can many other champs which can also build tanky after tri force effectively.

If your team was squishy in any way a tri force would pummel you, that's why bruiser builds are so monstrous against adcs and assassins (they can tank hits and deal decent damage).

With the items he had:

Deadman's Plate: gives him the initial movespeed to engage (not needing to burn his w or e) with decent extra damage on first aa.

Banshee Veil: keeps you from solo cc'ing him / makes it difficult for someone to shop his run in when it is up while also giving mr and health (health allowing his shield to become better).

Thornmail: is more effective due to the armour on deadman's plate plus makes the offensive of anyone who needs to aa him more dangerous and has a serious armour injection.

Trinity Force: has pretty much all you want: health, movespeed, movespeed on aa, crit, aa proc, attack speed, ad, ap and mana. All of these are more so beneficial for skarner as the ap and ad stack on his q (they both have ratios on his q), the movespeed allows him to keep up... im not gonna explain further but you get the idea.

The build skarner took was one which stifles anyone who runs against him not to mention his secondary is tank thus if he builds tanky he gets more effect out of it.

Jax wouldnt hold a candle to this because skarner's q does damage outside of jax's e and skarner has more cc than jax. In this case skarmer had resistance against most of jax's damage too (loads of armour for aa steroid that jax has and 60 mr to defend against occasional bursts of ap).

BTW don't underestimate thornmail's damage on a tanky champion / champion with a shield in this case does 37 damage due to his current bonus armour (not including masteries which adds a 10% bonus based on total armour - if taken) and then returns 15% damage back to you which is mitigated slightly by mr. So if your auto attack does around 200 ad late game it adds 30 dmg. even though this damage may seem small it adds up pretty quickly when the one with thornmail can actually take hits and is also fighting back.

Skarner did exceptionally well in building against your team (seeing as he couldn't be stopped) and probably played very well also. Please don't take a win away from someone just because you think their champ is op especially if they did well on their own merit.

Finally this is someone who has watched these builds be used many times and on different champions (the actual effect varies a little but not by much). I've also played against skarners also and completely shut them down (i also had the occasional skarner become a pain in the butt too).

I am not here to prove you wrong but give you another view as to why skarner was able to do what he did.

Oh, 70 Armor and MR for 8 seconds? How OP. Please, tell me how overpowered this is compared to Guardian angel, which provides similar stats, and a revive. This isn't really that much, especially if anyone can do decent damage.