Troll Lord Games

This is just me thinking out loud, but I know that some people aren't fond of multiple attacks, so I wonder if it's possible, instead, to allow the fighter to inflict additional damage with their attack instead. For example, at 6th, 12th and 18th levels, the fighter adds an additional weapon dice to their damage roll, so a 6th level fighter inflicts 2d8 damage with a longsword instead of 1d8, or 3d6 with a two-handed sword.

An 18th level fighter under this scheme would potentially inflict 5d6 base damage with a two-handed sword, which is pretty heavy but far less than many of the wizard's powerful spells.

This is an interesting idea, but remember, part of the benefit of the second attack is the fighter can use it on a second target. Such an advantage is lost under your proposal.

What if one combined it with a houserule allowing Combat Domination to be used for foes above 1 HD?

Option 1: CD is (CL/2)-1, rounded down, so a 4th level fighter can only attack enemies of 1 HD, but a 6th level fighter can attack enemies of 2 HD. This goes on until 9 HD at 20th level.

Option 2: Potential HD increases every 4th level after the ability is acquired.

This would allow the fighter to still be a potential killing machine with weaker foes (especially with additional damage).

You could port in a Cleave ability. Say you get a number of free attacks based on your level/3 to adjacent foes when you kill your original opponent. A 3rd level fighter would get two extra attacks after dropping an enemy. This would replace combat dominance but kick in at level 1.

See, I don't mind additional attacks in this system because the system runs so smoothly and fast. And, there's not 4-6 attacks per round that can be had. Two, three tops...that is, unless you're using some optional rules. To me, this is one of the premier abilities of the fighter, and I personally like it the way it is. Aramis raised a good point, about being able to focus on two targets, which is nice.