I've been lucky enough to get 2 of the Black Ibis Pieces, the Mask and the Boots. I got the boots at level 77 Thieving and the Mask after I achieved 99 Thieving, at 13.7M XP. I did manage to get a Sceptre of the Gods at level 92 Thieving, but lost it due to the destroy glitch it used to have if you had a full inventory. I managed to get a second one after they had fixed the glitch at level 98 Thieving. After achieving 99 Thieving, the next 700k experience it took to get the Mask was obtained solely from the first three rooms in Pyramid Plunder. I could generally get through all of the urns in the first three rooms, and a few into the fourth room. It's horrible experience, just breaking into the 30k experience per hour region, and I wouldn't recommend it at all. I now have almost 16M Thieving XP and have yet to get a third piece. The Sceptre of the Gods is a must have for attempting to get the Black Ibis pieces, otherwise you're going to spend the rest of your life there trying to get the set. I've recently given up on trying to get the set because although I love the looks of the set, I really can't be bothered with Plundering any more.