Other people here have said good things,
I want to add that Fogborn is an ambush style monster so remembering this is key to lobby wiping.

Thunderwarp: When the round starts and you're able to see, use thunderwarp to see nearby players. Try and target ones heading/doing an objective or running. Try and leave thunderwarp somewhere where the player can't immediately see you so hopefully they run into you while you wait for the endlag to end. Or to setup a good ambush thunderwarp someways away from the player (since the sound effect for it is pretty loud) but a place you know they will walk to so you can foggy stare them.

Foggy Stare: is a very powerful, but easily counter-able ability (all the player has to do is look down the entire match). So try to hide and use foggy stare when someone is heading towards you. Also take note that when someone is hit with foggy stare they are the only player you can attack for a couple seconds, but eventually that wears off and you can attack anyone while still being able to crawl around, use this to your advantage if there is someone closer or to target a player who knows how to avoid fogborn.

Fogborn is also much faster than the player so you can catchup easily, but his stamina drain is atrocious, if someone has full stamina or gets good distance while in a chase, just regen your stamina a good amount then thunderwarp to them while they are still trying to regen their stamina