I go warmogs on ahri since i go demonic embrace and HP helps it scale both in burn and a percentage of your HP gets turned into AP. it's not a lot of ap but it is some, it also makes you a lot tankier. Late game you have around 3500 HP and warmogs passive makes you great at joining teamfights getting kills and then going to either push wave or get any remaining enemies or objectives without having to worry about being low hp after a fight. this build seems in theory really low damage but what you wont expect it that you completely melt through your enemies hp bars and it's great at getting multikills. DONT UNDERESTIMATE WARMOGS AHRI

In lane when you start W you want to AA w AA to proc elec for free on your lane opponent this will already set your jgl up for a free kill if they choose to gank. A At lvl 2 you get your Q so your combo becomes Q W AA to proc elec. Try to poke them down with electrocute if they dont have any way to retaliate but if you're against a champ that can punish you for doing that just stay back and cs. When you reach lvl 3 if you have poked your laner down you can go for a flash charm (remember you can use your charm then flash to decrease the time they have to react) if you hit your charm your full combo+ignite should be able to kill them if you played lvl 1 and 2 correctly

Burn warmogs Ahri is decently tanky while dealing tons of damage in teamfights. You can easily dash in and eliminate the major threat on their team. using this build you will probably be pretty fed by the time teamfights start so you can probably use your ult reset to turn to get another 2 or 3 kills i reccomend you leave after that though since you will probably be too low hp to keep fighting after that. After exiting the fight you have 2 choices depending on the state of the fight. If your team can easily clean up after the damage you did to their team go push a lane or go to any objectives your team will go take and go start it. If your team cant clean up the fight with ease wait a few seconds while staying near so your warmogs can regen your hp so you can go in with full hp being the same monster you were the first time you entered the fight.