I also want levels of notifications. Especially emergency one - Some channels are super critical and I want to be notified immediately, give me a popup, ring my phone, override if my phone is on mute, then call me. Kind of like pagerduty.

Arbitrary regex matching. Something I use in IRC often.

I lurk in a bunch of Discords for things I'm not active in, but don't want to have to find an invite to if I need to ask a question in the future.

I always have a notification badge on Discord, and I hate it. Too many servers have channels where I get pinged, even though the channel is muting. I'm presuming someone is doing something like "hey @all, play with me"

I ought to be able to register that I will never ever care about this channel. Please ignore it for me.

You can mute channels and servers completely and get no notifications.