Quick question on warlock dc

[pwdcrk1]

Maybe I just remember wrong

But isn't that after a certain level all invocations were counted as level 9 ones to bump the low dc of warlock ? If I remember correctly was a customization of BG is still This way ? And which is the level that one have to reach ?

[flyingchair]

As a level 27 warlock i have yet to reach this level :S, so if its there it's 28 or up