Is it better to build Mallet or Triforce? His ganks arent that good due to the lack of CC so im thinking about Mallet instead of triforce for the slow. Also, Heca is a great tank late game but his damage is too low. Should I build a Maw or anything or stick in tanky build?
It all depends on what your team needs from you. If your carries are doing well and you've got a DPS-oriented bruiser type, then you're best used as a damage soak and you want to be as tanky as possible. But if your carries are behind, or your overall team DPS isn't so great because you've got more tanky/utility champs around, then you want to build some damage so you can help out more.
Mallet, Triforce and Maw are all valid options really, and if you think "one of them is always best" then every once in a while you're going to run into situations where your build is not optimal for your team. Always look at the bigger picture, and ask yourself what your team needs from you at the time.
Triforce much better. Helps for incredible boost in damage output throughout all stages of game. I usually get sheen as my 2nd/3rd item and then build a few tank items first.
You need to practice setting up good angles for your E. He is one of the few champs who can run by a ward, completely seen, but act so fast the lane has little time to respond. E+R can give you so much mobility. Make sure you place your ult just beyond their champ, as this will make them be feared backwards toward your teammates.
Triforce over mallet, but only if you are getting some early kills can you rush triforce. In a normal evenly matched game, usually I'll get a sheen then work on a tanky item such as glacial shroud or hexdrinker before going back to the triforce.