Who are Fighters and Mages Strong against?

Mages > fighters Fighters > Assassins

^ yah I agree with this

Classes aren't strictly strong against other classes. Yes, ADCs are weak to assassins. They're also weak to basically anyone with burst or lockdown - many fighters and mages, some tanks, some other ADCs Yes, ADCs on the surface seem to be the best tank killers, but many of the best tank killers actually belong to other classes - Fiora, Trundle, Brand, Malzahar, Vel'koz, etc. Most of the time, being able to kill tanks is something you itemize into.

I wouldn't say mages and fighters beat or lose to any other class, I feel like their place depends on the whole team. Mages are generally stronger when grouped in teamfights and fighters are stronger when in small skirmishes. They don't really fit into the whole triangle. Fighters kinda tend to beat up everyone, but are bad at grouping. Mages are generally weaker at 1v1s, if you can survive their burst, you lose. (yes this is hard when fed)