The grisgol: a high-level construct whose creation requirements include a ton of gold, some XP, a bunch of spells, and a phylactery. That's right, hunting down a lich and their phylactery is a requirement for even starting on the creation of a grisgol. Considering that if your fancy new toy ever ends up being destroyed the lich is free to reform, I'm not sure why someone would ever take the risk of creating one of those.
To be honest, I'm conflicted about the grisgol. It is kind of underwhelming all-around, with incredibly low stats, tons of construct RHD, and weak natural attacks (1d8+1d6+5 base damage with a paralysis rider is nice, but those guys aren't built for melee). Immunity to Magic is the double-edged sword it's always been, Choking Dust means you're a walking party health hazard (also, why are you in melee), and the DR is nothing extraordinary (though DR/piercing is pretty rare).
However, then there's the creatively named 'Spell-Like Abilities', which singlehandedly makes the grisgol interesting. How? By granting it any one wizard/sorcerer or cleric spell of each level, usable as a SLA 1/day. This is an ability so powerful I'd argue it turns a grisgol into a low tier 2 character without much effort. Even when the obviously problematic spells are ignored (Wish, Gate, Miracle, PoA), this ability is still very powerful. Do, however, note that the saving throws are entirely based on the spells' levels, rather than the grisgol's casting ability or HD.
That said, each one of those being 1/day is obviously a drawback, and without them a grisgol only has its awful slams to fall back on. The sole level they can take before going epic isn't much help either. I'm not saying there aren't spells that can't help in multiple encounters per casting (Shapechange, Greater Planar Binding), but being forced to pick those will limit your options.
Aside from abuse of a few choice spells, the grisgol is not competitive at ECL 19, not even when compared to tier 3 classes. -0* LA.