Yes, it raises vitality not vigor. Vitality increases instant death resistance. Vigor increases health.

You don't have to die, there's a ladder that leads out the boss room right near the item.

Root guardian drops a golden seed if beaten.

Vitality does not give you HP in Elden Ring, Vigor is what gives you HP. Vitality is a Resistance type stat that gives you protection against instant Death status effects (like Curse in DS3). So this talisman will boost your resistance against death. Check the Vitality section here https://eldenring.wiki.fextralife.com/Stats or in game.

It increases Vitality, which is a stat that has death resistance (not sure where it happens yet, but it seems like a build-up thing like Poison etc.)

Death/curse in the souls series is a ailment that builds up causing death.

To answer the ���used up talisman��� question. In Elden Ring talismans are just like rings in the rest of the DS series. They last as long as you have them equipped.

You'll know by now, but if you really wanna see the stat change yourself, make sure to flip through your tabs with "Y/Triangle", when you're on the equip screen.

You'll see the vitality stat change there.