whirlwind attack and spiked chain

[Kastumoem]

In the group I am currently DMing a player is working towards whirlwind attack and wants to get a spiked chain to use with it, I'm just wondering how I should handle this situation should I let them get the chain and be able to just use it with whirlwind attack without any penalties or additional training required (beyond standard proficiency), or should they have this extremely powerful combo with just the feat and proficiency with spiked chain?

I know i could just make it less likely that they will be able to use it or make them take penalties if their allies are in the range but I'm not sure quite how to approach this...

currently the character is a level 3 fighter and has combat expertise, dodge, mobility, and EWP(Bastard sword) and plans to take spring attack at 4th level and take whirlwind attack and EWP(Spiked Chain) at 6th.

[Jayef]

There are so many required feats that I don't consider this a "powerful" combo at all. Consider that this player is spending SIX feats to be able to do this.

[Raphir]

That's actually a pretty interesting combo... Never thought of that one. Getting to hit everything in a 10 foot radius is pretty sweet.

I have to agree with Jayef on this one: even though it is a powerful combo, he's paying a due price for it. You can make combos that are much more annoying with that many feats. Plus, it makes good sense in terms of D&D rules and fantasy world physics, so to speak (not to mention the cool factor of having a character swinging a chain around against monsters).

As far as whirlwind attack goes, though, I always go in favor of saying that if any of his allies are within the range of his weapon, the character HAS to make an attack against them as well, no matter what weapon he's wielding. I mean, the hole point of this attack is swinging your weapon around very hard and very fast, which doesn't help when it comes to NOT hitting stuff in that area. Again, this is in line with the visual effect of having someone swing a chain around: even if you're his best bud, you might want to be at least 10 feet away.

You can always rule that he needs the full length of the chain to properly execute the attack, too, so you could make it so he always has to have 10 feet of room around him to use his combo, so you can just shove him in close quarters whenever he's giving you trouble (he'd still have his bastard sword for that though). It's also always good to remember that whenever there's only one monster involved in combat, whirlwind attack is useless. He'll regret not getting Weapon Specialization whenever you pitch a dragon at him.

All in all though, I say just let the guy have his fun with this combo.