Many of the high CR creatures in the MM2 are overrated for their CR. The mountain giant has a pathetic will save and no SR. Many of the undead don't have the hp or damage output to warrant their high CRs.
The deathbringer has no SR and no real damage output. The best thing it can do is greater dispelling until it is destroyed. One would imagine that the deathbringer could use greater dispelling to debuff the party before wading in for melee. The creature looks like a melee monster, but with a +16 as its best attack, it won't even scratch most 17th level fighters. Perhaps you could surround it with lesser undead, but that doesn't make it a CR 17.
The deathbringer has no SR and no real damage output. The best thing it can do is greater dispelling until it is destroyed. One would imagine that the deathbringer could use greater dispelling to debuff the party before wading in for melee. The creature looks like a melee monster, but with a +16 as its best attack, it won't even scratch most 17th level fighters. Perhaps you could surround it with lesser undead, but that doesn't make it a CR 17.