No

that ring only works with Sorceries, this is a Pyromancy, not a Sorcery, so no

Technically untrue. The Lingering Dragoncrest ring affects Pyromancy self-buffs such as Iron Flesh, Power Within and Flash Sweat. I don't believe it has any effect on this spell's duration though.

can confirm lingering dragoncrest ring seems to have either so little it's negligible or no effect on this spell, I tested it on the same crossbow hollow next to the undead burg bonfire under wyvern bridge

I know this is hella old but yes, I also highly suggest you look at red Rosie's video.

It’s very useful outside of boss fights, and it’s always fun to use it when your invaded

"It's very useful outside of boss fights and it's always fun to use when you're invaded"? Bro, you can't even affect any enemies that are a threat to anyone.

Can be used in one boss fight actually. Taurus demon in NG+ has two undead snipers on top of the tower.

Taurus demon's tower archers

It’s definitely worth it, the chaos of there being another entity on your side makes a lot of fights a lot easier, most of the time they won’t even survive the 30 seconds so it will be until killed, unless there’s no enemies left in aggro range

the duration is more than long enough, the enemy usually dies before that time runs out anyway. The biggest problem with it is that you have to get really close to an enemy to use it, at which points you end up taking damage...

It'd be a viable PVP weapon that way. Imagine being invaded in Undead Burg, only for the poor idiot to be gangbanged by every Hollow in the city...

if only, you can only have one at a time, but it would be effective if you got one of the spear hollows to sandwich them because they wouldn't recognize it's a threat because they rarely attack

Imagine if they limited a spell to a specific gender, that'd really suck.

go to horny jail *bonk*

As weird as that might sound, skeletons are technically not undead in Dark Souls, they're just called "dead", since the word "undead" has a completely different meaning in Souls.

It's surprisingly helpful in Duke's Archives. I can also see some use for it in Ariamis.

But yeah, it's mostly for messing around.