Bat Familiar Bonus Senses and Fog Cloud (2024 rules)

I'm not sure about the idea of needing the bat near to you, your not really using bats eyes your using it's echolocation (Think Daredevil) so your using it's hearing to locate your opponent, plus it would be pointless as you could just use the bat to preform the help action giving you advantage, you could also just use a touch spell, Arcane trickster has two touch spell cantrips Chill touch and Shocking grasp, so you can either use your bonus action to use the bats echolocation (which could give advantage depends on DM if not then) use the bat's action to help you which will give advantage if combined with the bat's senses, but if all else fails just use a touch spell as you can cast the spell using bat's reaction which has no problem finding and attacking the enemy in the fog which again should be at advantage.

Attacking outside the fog is a bit different, you won't get advantage and the bat is vulnerable if it leaves the fog but you should still be able to use it's senses to locate anything outside the fog that is about 60ft away, If I was a DM and had to counter this style of play then I would get the enemy to use the gust spell or something similar to disperse the fog, have the enemy escape the fog and use a AOE attack to drive the player out or, use something that will cause the player to be deafened stopping them from using echolocation and leaving them blinded.

Quote from jamesnsmclean >>

[...] Attacking outside the fog is a bit different, you won't get advantage and the bat is vulnerable if it leaves the fog but you should still be able to use it's senses to locate anything outside the fog that is about 60ft away, If I was a DM and had to counter this style of play then I would get the enemy to use the gust spell or something similar to disperse the fog, have the enemy escape the fog and use a AOE attack to drive the player out or, use something that will cause the player to be deafened stopping them from using echolocation and leaving them blinded.

 Not sure if I'm missing something in your explanation.

Fog doesn't create Cover, so I'd say you should still be able to use its senses to locate anything inside or outside the fog within about 60 ft.

That's okay my explanation was about if the DM decides you don't get advantage on your blindsight you still have other ways to get advantage, sorry if I did not make that clear.

Quote from jamesnsmclean >>

That's okay my explanation was about if the DM decides you don't get advantage on your blindsight you still have other ways to get advantage, sorry if I did not make that clear.

 No, no, it's fine! Thank you!

it's perfectly legitimate and used as intended in my opinion.

I fully agree, but sadly DMs get to make the finale decision so that's why I explained other options to get advantage, but hopefully if the DM keeps to the rules you should only need to share senses with your bat to get advantage.