I play Pantheon with the meta items and even off-meta items to test his damage output. When I watch in-season videos or friends play him he's an insane crit/stomping machine but when I play him it feels like his damage output just isn't good without gank assistance or team fighting.
I want to play Pantheon but is he even good in this meta? Can I get some pointers?
I've had pretty good success playing 
like an assassin with this build: 
. Basically, you just go in, delete one person, get out, and wait for your cooldowns.
Trade early on when the enemy dont has much besides auto attacks; Make positive short and bursty trades. kill enemy laner repeadetly. Roam mid at lvl 6 with ult.(if you have tp, try to tp bot first with 1 kill for you and 1 for your adc. buy youmus; take towers asap, and always dictate the enemy your game pace(dont let them act; force them into reacting)
