This build will make you extremely tanky early on and deal really heavy damage mid to late game. At the start of the game it's a good idea to build quite tanky and leave the bulk of the damage to the laners when you gank. Try to gank often with Skarner, everytime your ulti is up you should be ganking someone. Be sure to focus the damage dealers with your ulti. Sometimes it can be a good idea to let the team burst down the squishy carries and then ulti the bruiser who is tanky. This way, the carry is already dead and the bruiser who would otherwise escape also ends up dead. HOWEVER, if the ad carry is snowballing, just go ahead and ulti him anyway because you have to prevend him geting kills whilst minimizing damage to the rest of the team.