Question about Cubics. . .

Ok, so from what I've been able to tell cubics require this thing called spirit ore. But while browsing the skills list available to me at http://www.l2archive.com/skills/, I noticed something peculiar. I'll just quote the skills:

Summon Life Cubic Lv. 2
Cost: 44 mana
Summons a Life Cubic. The Life Cubic uses magic to regenerate HP to its owner and party members. Requires 6 Spirit Ore.

So, it clearly mentions it costs spirit ore, and how many. Now:

Summon Knight Cubic Lv. 7
Cost: 115 mana
Summons a Knight Cubic. The summoned cubic recovers 6% of Max HP, removes debuffs from you and makes you immune to debuffs for 6 seconds. Also P. Def. and M. Def. +500.

Basically, the knight cubics don't say ANYTHING about costing spirit ore. Which leads me to my question. Was the site just being lazy and omitting the cost of spirit ore as a given? Or are you rewarded in higher levels of play as a tank by being able to summon knight cubics (which are pretty awesome) with just mana and no need for spirit ore?

I think that the knight cubic doesn't cost anything. Anyway, from what I heard it's not that good as the description says. Some say that the smart cubic is much better. you get that healing effect only at lvl 95, or smthing like that.

Thanks for the response. ^^ I posted this question on the elven fighter forum a couple days ago, and it seems pretty quiet over there.

But your answer has put a very important question for me to rest, and I appreciate your answer.