Max level: 65
Max Att: 175 (+5/3 per lvl)
Max Def: 58 (+1 per lvl)
Max Dmg: 203 (+3 per lvl). Double damage bonus = 406 max dmg.
Along with the Rod of Ruin, the Wand of Endless Suffering is the only weapon in the game with a double damage-type bonus. This causes its DMG stat to be doubled in effect, making this wand among the strongest offensive weapons in the game.
For this reason, it's considered the best weapon for the Warlock, superior to the tier 2 wand, the Graymarrow Wand. It's possible the Graymarrow Wand will outperform at max level and enchantments, but even then, the difference should be small enough that adapting the tier 2 wand is low priority for the effort involved.
The double damage contribution is so significant, that the Warlock's shorter cooldowns, which allow her to more frequently apply the double damage type bonus, make her preferable to the Archmage for most of the game, in spite of the Archmage's skills having higher base attack.
The Wand of Endless Suffering requires level 45 to craft, overall the second highest of any T1 epic item after the String of the Gods.