Attack bonus
- +2 BAB (from 3 levels of monk)
- +3 Dex
- -2 Two-weapon fighting with a light weapon in your off-hand (unarmed strike)
+3/+3
Attack bonus with a Flurry of Blows
- +0 BAB (from 3 levels of monk, Flurry of Blows column. You don't add it, you use it instead of your usual BAB whenever you use the Flurry.)
- +3 Dex
- -2 Two-weapon fighting with a light weapon in your off-hand (unarmed strike)
+1/+1/+1
Damage bonus
Depends on your Str bonus. Let's assume +2
- For two handed weapons it's 1.5 times your bonus, rounded down.
- For unarmed attacks it's your bonus, because monks don't halve it.
So:
Attack 1 (spiked chain, main hand, finessable, reach)
- 1d20+1 to hit
- 2d4+3 damage
Attack 2 (unarmed, finessable)
- 1d20+1 to hit
- 1d6+2 damage
Attack 2 (unarmed, finessable)
- 1d20+1 to hit
- 1d6+2 damage
Horrible, I know. But that's what you get when trying to use early on features and feats that decrease your chances to hit in order to get you more attacks.
A note on weapon proficiency
In 3.5e if you're proficient with a weapon you get no bonuses. If you're not proficient, you take a -4 to hit instead. Luckily, monks are proficient in every monk weapon, and your DM included the spiked chain in this number.