How are monster’s skills calculated?

Question

For example, I’m looking at the Goblin Hex Hurler found in the Monster Vault. Its skills are Stealth +10, Thievery +10. The Monster Vault states:

The skills section of a monster’s statistics block includes only trained skills or skills for which the monster has an unusual modifier.

Assuming the monster is trained in the skills (+5) and with an adjusted Dexterity modifier of +3, I’d expect the values to be +8, not +10. I thought this may be a racial bonus for Goblins, but the Goblin Sniper, Goblin Beast Rider, and Goblin Cutthroat all have only +8 to these same skills. Where is the remaining +2 coming from?

Answer 1

The other goblins are missing their racial bonus.

According to Monster Manual p.278, the goblin has +2 racial bonus to +2 Stealth and Thievery. It's correctly reflected in all of the goblin statblocks in that book.

The Monster Vault statblock for the Hex Hurler correctly includes the goblin's +2 racial bonus to Stealth and Thievery. The Goblin Sniper, Goblin Beast Rider, and Goblin Cutthroat which are missing their +2 racial bonus.

Why? The best I can surmise is as follows.

The Sniper, Cutthroat, and Hex Hurler originally appeared in Dungeon #180 (Jul 2010), which pre-dates Monster Vault (Nov 2010) by a few months. Of these, the Goblin Hex Hurler is fundamentally the same as the Goblin Hexer from the Monster Manual, with some tweaks. The reason why the Hex Hurler has Stealth +10, Thievery +10 is certainly that it's based on the Hexer, which also had +10.

Dungeon #180 also had the Goblin Cutter, based on the Goblin Cutter from the Monster Manual, except for slight numerical tweaks. Notably, its Stealth and Thievery skills are increased from +5 (presumably +3 Dex, +2 racial, no training) to +8 (perhaps +3 Dex +5 training, forgetting the racial bonus in error, since it's not listed in the main Goblin entry in the MM). Then again, it may also be that the author arbitrarily increased it from +5 to +8 for game balance.

It also had the Goblin Warrior, who retained their +10 bonuses to the two skills from the MM. My hypothesis is that the Cutter was changed because the author mistakenly assumed the +5 was an error (+5 training, no Dex), but they left the +10 because that was clearly good enough.

Dungeon #180's Goblin Cutthroat also had +8. It's bizarre to see its statblock right next to the Goblin Warrior, because both of them are level 1 skirmishers with the same Dex modifier, so you'd think someone would have noticed. The Beast Rider seems to be new to Monster Vault, and its skills are no doubt copied from another of the goblins with +8.