In the description of the Necromancer talent Deathknell, there's a table saying "3rd level spell", "5th level spell" etc. etc.
This has got me confused, as I didn't think Deathknell was a spell.
So, what does it mean? Does it mean you have an extra At-Will spell you can choose (or not) to take, called Deathknell?
Does it mean it just automatically upgrades as you level up?
Does it mean something else?