Defeating party AC with 1 HD Hobgoblins
Ok, so Low 20's for most, one 18, and a Monk at Ac 30. With some effort, all but the monk should be fairly easy to score hits on. Lets say the standard AC is 22 for your party.
First start with a standard hobgoblin (using 3.0 stats, probably still accurate).
Hobgoblin Soldiers: CR 1/2; Medium Humanoid (Goblinoid); PG 119; HD 1d8+1; HP: 5;
Init +1(Dex); Spd 30ft; AC 15; Bab +1; Atk +1 LongSword 1d8,Tht 19, (S),
+2 Javelin 1d6, (P) Face 5ft/5ft, Reach 5ft; SQ (Dark Vision 60ft),
AL LE, Saves Fort +3, Ref +1, Will +0; Str 11, Dex 13, Con 13, Int 10, Wis 10, Cha 10;
Skills: Hide 1, Listen 3, Move Silently 3+4, Spot 3; Feats: Alertness;
Eqp: Studded Leather, Small Shield, Long Sword, 3 Javelins;
So obviously, standard issue is not too bad, but no so good. Looks like under normal circumstances, he can probably hit only one of your players with any reliability. Lets customize as an archer:
Hobgoblin Archer: CR 1/2; Medium Humanoid (Goblinoid); PG 119; HD 1d8+1; HP: 5;
Init +1(Dex); Spd 30ft; AC 16; Bab +1; Atk +1 Shortsword 1d6,Tht 19, (S),
+4 Longbow, Crit x3, (P) Face 5ft/5ft, Reach 5ft; SQ (Dark Vision 60ft),
AL LE, Saves Fort +3, Ref +2, Will -1; Str 11, Dex 14, Con 13, Int 10, Wis 9, Cha 10;
Skills: Hide 2, Move Silently 4+4; Feats: Wpn Focus Long Bow;
Eqp: Studded Leather, Buckler, Short Sword, Longbow;
By kicking up the Dex one point and using Wpn Focus on his long bow instead of alertness, we are at +4 to hit. So your now scoring hits vs AC 22 on an 18 or better within short range. You can use a Bard or a Bless spell and get a +1 Morale. A 5th level preist can cast Prayer for a +1 luck bonus. So with Bless/Bard + Prayer you can get the following:
Longbow, +6 to hit, 1d8+1 dmg.
Using my suggested maxed out Expert Tactician for support with a Prayer spell active with these archers, you can get +11 to hit and +5 to damage. That should be plenty to land hits on your PC's at Ac 22 or lower.
And that is with a 1/2 HD Hobgoblin with minor modifications.
To get better than that your going to have to find ways to deny the Dex bonus. If you can force the players to be 'off balance', your archers get a +2, ditto for climbing, and the targets get no AC bonus from Dex. Try to find some way to disable or damage the players shields and / or armor if you need to improve this.
If you want to be Evil, throw some poison on those arrows. Small Centipede poison is probably reasonable for Hobgobs, but a DC 11 fort save just wont cut it here. Go with the Giant wasp poison at DC 18. 1d6 Dex dmg initial, and another 1d6 Dex secondary will add some AC loss.
The big problem is going to be the Monk. At AC 30, he is pretty much untouchable. Given that it is a Monk, AC 30 is probably going to count as the touch attack AC as well. So your probably not going to score with a tangle foot bag or Net. On top of that, with a monks movement rate, your not going to get a whole lot of success with attack + half move retreats. And to further complicate things, your going to be hard pressed to overcome the strong saves and cause ability damage to cut the AC. I will admit that at this time, I just dont see a way to make 1/2 HD Hobgoblins viable threats to this character. Your Hobgobs are just going to have to find a way to cancel the magic items that are pumping the AC here (at AC 30, at least half of that must be from magic items).
END COMMUNICATION
