Trynd is slightly overpowered, but currently NOT the most OP champion in league. He is simply hard to counter, and is incredibly versatile, being capable of going top, jungle, and sometimes even mid. However, any champion with a high enough burst to keep him from farming in lane is more than strong enough to deny him enough to counter him, however, he snowballs really easily since he technically has unlimited HP for 6 seconds when his ult is on, so if his team can pick up his slack, if he's not doing so good, then yes he is very capable of carrying teams