The 10x thing is just a basic requirement for an ascended attack. Basicly, your physical strike should be 10+ times higher than the targets physical defence. If it is not, you will not be able to hit the target. Rank mod does not apply here.
About killing LF...
So you succesfully hit the guy. Then, first the targets Personal Def Skill/Level activate and reduce the damage you did. Then, the Repulsion activates, further reducing the damage. Finally, the Personal Constitution activates, further reducing the damage.
For example, if the target has researched 500 to all said levels, then target will suffer only 31.5% of the initial TOC.
But it is not over yet. Ascended Life Force (ALF) is damaged before the reserves. Which means, after the hit, you should take the target's ALF off from the damage you did.
Another example. I hit the guy from the previous example with my 750M TOC. The actual damage I cause is 750M X 0.315, so 236.25M. But said target has let's say 60M ALF, which is taken off from the damage.
Summing it up, you hurt the target's reserves by 176.25M.
Lame, isn't it?

Colos