Trundle is an AD Offtank which specializes in stealing enemy stats to benefit him and his team.

These runes were specifically picked for extra damage and lane sustain.
his passive combined with the lifesteal quints make him very capable of staying in his lane without needing to back. (but go back if necessary)

Pros:
Huge sustain
able to steal stats
Cryptonite to anyone that specializes in close combat
his kit was made to troll enemies.
He can make tanks squishy!!!

Cons:
susceptible to ganks
weak against champs with ranged skills (gp, kennen, vlad, ect...)
Becomes weak in late game

Trundle's farming is exceptionally good because his Q raises his atk power which makes it more efficient for last hitting.
You have to be killed a lot to be outfarmed.

Trundle can be amazing in teamfights as his ult can make even the tankiest shen into a easy kill for the team (giving him extra tank might i add) and if he manages to chomp the ADC, it will severely cripple their atk stat and make you even more of a threat. Your E is only there to secure a kill or escape. Now for his W, his W is freaking amazing, gaining movespeed, atk speed and extra healing, your ult combined with the support's heal. (if the support can heal) It would pretty much restore you to full in less than a second!
Be careful though. As you will most likely be focused if you get split up from your team, as Trundle is still very squishy if you don't have your tank items.

This my first guide ever. But you may doubt this build as I am still in Bronze III but I can assure you that i put my heart and soul into this game and hope this build helps you win.