immolate - what levels for burn times?

I see immolate is changed now to be 1-4 seconds. I keep upgrading my pyro fire attributes but I still only burn for 2 seconds. I'm level 15. I searched the forums and other places but I only ever see the 1-4 second rating, but no mention of how many attribute points your need to attain 3 or 4 second burns.
Does anyone know how many attribute points you need to get higher second burns? I think I may be misunderstanding how DoT spell length is calculated...

Thanks for any suggestions.

it still says 3 seconds everywhere i just checked.

level 12 should get 3 sec.

http://www.guildwiki.org/wiki/Immolate

Er,... ya. Now I can't find where I saw it was changed to 1-4 seconds. Sorry about that. Thanks a _ton_ for the link.

I'm not doing so well in pvp in the lvl 15 arena - esp with so many wearing Droks armor most of my spells can't harm them. Immolate gets past it but I wasn't sure how much damage I was doing.

I see it's from 5-41, but the chart goes to 59?

Hmm, further reading shows -7 health degen for each second. So I do 32 damage initially and -14 hp/s after that. So it seems I do want to get to a lvl 12 3 second burn... Total damage would be 41 + (14x3) = 83 unstoppable. At least that's one useful thing I can do against Droks warriors.
(At least I think it was Droks, fireball was doing like 2 dmg to one guy a couple of nights ago in the lvl 15 arena!!! <confused>)

Thanks again - it has helped a lot.