If a creature can rend after making two successful attacks (in the same round), but the creature has a high enough attack bonus that he has 3 attacks, would he still get the rend ability if he was making all three attacks?
(as in claw, claw, rend and claw)
That sounds right... But, to my knowledge, usually those creatures with the Rend ability have claw/claw/rend (if both claws hit)/then a bite. Natural weapons don't seem to have extra attacks for high base-attack bonuses. I'll have to look it up when I get back from work.
Ultradan
Natural attacks (like claw, slam, bite, gore, etc.) don't get more attacks from the creature's base attack bonus. Either a creature has 2 claw attacks, or it doesn't.
In any case, the rend ability (which usually works based off of a specific natural attack the creature has) comes into play any time that particular natural attack successfully hits twice in one round.