this is my build on kog'maw , focused on DPS , he is hard to use but can kill any champion 1 on 1 when your good at it , hes cheap too , so i recommend him for everyone
this build is not yet finished , so please if ocmment if it still isnt helpful , then wait

you must ALWAYS be mid , or solo , no matter what you do , if it cant be helped and their too stubborn to listen , kill the wolf creeps to get an XP advantage , dont forget to pop one of your potions to NOT get killed by them , then immediately teleport using your teleport skill , that will get u an advantage (even just a little) , it might even get you early kills , and it is impossible to NOT get killed by your enemy in laning phase , just remember to teleport to your minion and take that kill back , or gank someone at the top or bot to help them out and get you kills / assists , only LAST HIT minions , you will get pushed but its worth it ,

HEAL AND TELEPORT , teleport to lessen your XP loss when you die or recall , and HEAL to add to your survivability at early game , its also useful to lure greedy enemies into the tower and then press E and heal up immediately , it would get you a good chance to kill/assist , and one of the greatest uses of it is healing up almost dead allies in a clash , its like a medic skill only that your not a medic but a cold blooded merciless killer trained to kill low HP enemies under 3 seconds

basically i use focus on offense , and heal (coz thats what i use besides teleport) well thats coz this build is based on him DPSing , hes a monster , a literall monster that can kill enemies within 2 seconds , NO dps can match him once he's middle , unless its lategame and u didn't get to farm much during the time you roamed and ganked

i focus on his Q , since the bonus for attack speed is VERY VERY VERY useful in EVERYTHING he does , its a lot better than tristana's Q or miss fortune's W since its passive , then comes void ooze since its good for farming (example 2 creeps r below 50 hp and u want to get them both) and its good for harrassing (slow them then come to them [obviously they will run] press Q then W and then get 1/3 of his HP (or if your too fed up with gold , kill him) , then do the same over and over again and use your R to finish him off once he recalls

i use crit chance because its the most useful thing for me , once i get phantom dancer then my crit chance is gonna be high up already , even at the start of the game its already high enough to get a few crits , it can also be a lifesaver (for example you hit one of the minions with above 100 HP and another minion is going to attack it , it just might crit)