13+ for Attributes

Does going over 12 Attribute points really increase the effectiveness of the Attribute and its skills? Also with a major rune that adds 2 to an Attribute does that really subtract 50 health ?

yes to both questions

a superior rune is 75 off

EDIT

and before you ask

yes it is worth it to the people who do it or they wouldnt be doing it

Most people use a suppior vigor rune (+50 hp) to offset the -75 other suppior rune. Suppior runes are really usefull for everybody but warriors, since warriors want the most hp they can get. +3 to an attribute increases a skill quite a bit.

And there are upgrades to weapons that provide health. Just another way to balance out the minus health from major and superior attribute runes.

just to make a list of + attributes:
+1 helmet
+1 Minor rune
+2 Major rune -50hp
+3 Supperior rune -75hp
+1 weapon with % chance
+1 weapon with +1 while useing a specific skill
+1 focus with +1 while using a specific skill
+2 Awaken Blood (skill that gives +2 for a couple seconds)
+2 from another skill like awaken blood but i can't remember the name

I think that is all of them.

Well thank you all for the responses, its nice to ask a question then go to dinner and then see all the answer you need when you get back.

Glyph of Elemental Power is the other skill that gives +2