“Block his Q with your E and be careful when he ults you as it removes some of your resists and drains your hp over time. Don't give him lead in lane and you should win him. ”
“TL;DR - SKILL MATCHUP. CONQUEROR IS RECOMMENDED HEAVILY. DON’T FIGHT HIM EARLY. STELCAPS->BRAMBLE IF YOU ARE GETTING DESTROYED. BE CAREFUL OF HIS PILLAR. DON’T UNDERESTIMATE HIS ULTIMATE.
He is similar to Olaf in that you should be keeping trades short early on. Try to just Q him and back off, because a PTA Trundle can beat you up very quickly. His DPS when you allow him to constantly auto and use his abilities on you is staggering so you really should be kiting well against him. Try to fight him after he uses his Pillar, as then he will have no way to slow you down/escape. As I mentioned before, you should be looking for Qs, as he doesn’t really have any way of avoiding them if he is going for minions. His ultimate can be surprisingly powerful at times as he just steals ur stats so it might not be the worst idea to simply try to disengage and then fight him again. Trundle also falls off super hard so there’s THAT to look forward to. He is very good at setting up ganks due to his Pillar so try not to walk around walls to much so that he can’t just completely block you off. Steelcaps are a great buy into him and if that isnt enough, Bramble vest is another great purchase if he is ahead of you. If you are ahead, you can freely buy damage. Conqueror is recommended, as both the extra damage and the healing are nigh mandatory.”
“Will bonk the life out of you if you're not careful. Bramble is good here. MAKE SURE TO ONLY ULT AFTER HE ULTS AS HE WILL STEAL MORE STATS FROM YOU IF YOU ULT FIRST.”
“Free Lane: Keep your distance and watch out for his Pillar of Ice (E)”
“Trundles R its complete as* as Cho'gath.
It steals a part from your Max HP and steals your armor and MR.
However you can Burst him with the true damage from your ultimate and with a morello or thornmail you deny his healings.
If going tank get a thornmail, if he is going full tank/support just adapt to what you need in that game.”
“Pretty free. He can duel you late game but early and mid should be yours. BORK very good option against him.”
“Rush Tabi and try to block his Q with your E. Remember that his ult removes some of your resists and drains your health over time. Executioner's Calling can be useful vs his huge healing from every source.”
“Make short trades with Trundle. Avoid fighting in his Frozen Domain(W) as he gains Attack Speed and Movement Speed bonus. Dodge his Pillar of Ice(E). Avoid fully fighting him whilst he has Subjugate(R) on. If you have another tank on your team try to avoid building too many tank items due to his R. (Outscaling Edge: Even) (Sustained 1v1 Trades: Even) (Recommended Items: Morello's or Thornmails)”
“Parry his Q to deny massive damage and to slow him. When he ults, run away unless you can kill him fast. Give him ult respect throughout entire game unless you are really ahead.”
“The only annoying thing is how if you're not ahead he will run you down and block off your escape paths. He steals your stats at level 6, and if he builds Trinity it's scary how fast he attacks. But you should never run into those problems because you win early level fights. To start trade use your Q into E and just punch him. He needs to walk away after that, because if he attacks you, you will just W him and he will lose the trade harder. When he's low, if he lays down his domain to try and get away save your E for that. Diving him can be tricky because of his pillar and ult, but you can kill him pretty fast, especially if you collapse on him with multiple people. He doesn't have much of a use in team fights other than separating people on your team and chasing them down. But you hard counter that because when he walks up to your team you just ult him back to Troll Town. The main scary thing about this matchup is how fast he takes turrets, especially with the new Trinity Force. Be aware of him splitting, and never leave him be there, because your turrets will be gone in seconds. Collapse on him with one other team member if he tries to keep splitting, but don't chase him too far without vision of where the enemy team is, it could be bait. Take Bramble early for his ult, and Plated Steelcaps preferred unless you really need the Tenacity and MR from Mercury Treads. Trundle will build Trinity Force (unless he's an idiot) so you need to match that. Your 1v1 is stronger than his with the same item, so he'll never be able to beat you unless you like completely miss your W or something stupid.”