The headache, for me, is figuring out what to allow for a given campaign.
Let’s say we run a superheroic game. Presuming that a key element in allowing Combined attack is that character by their attacks/powers with character points. And are not limited by Power Frameworks, both are HTH or range attack and use similar attack roll… We have the following cases.
Energy projector, with a Blast and Flash power. This is the classical case, and if not limited by PF, he should be allowed to use them in a combined attack.
Weapon master. Dual wielding and bought his weapons with CP. Is not required to buy skills for them. 5th Ed R p.373 makes a strong case for it. He should be allowed to use them in a Combined Attack and not be affected by off hand penalty. What if he picks up similar weapons but not the one he payed points for? He might even be skilled with them. Should he be allowed to us them in a Combined Attack? Probably not…?
Martial artist. Might have a few abilities bought as powers but the bulk are bought as Martial maneuvers. . 5th Ed R p.359 says the maneuvers can be combined as long as the effects are not similar. Legsweep + Martial Disarm is ok, but not Strike + Legsweep. This gets a bit more complicated and might require a lot of GM ruling during play. Not ideal. 6th Edition simply forbids it. Is that fair if the previous characters are allowed?
Now, for heroic campaign. Most attacks are made by weapons bought with cash. Skills are bought to used them. Combined Attack should not be used. Off hand penalty should be applicable. If proficient in Two-weapon Fighting skill, it allows the use of Multiple Attacks. 5th edition does distinguish between campaign that allows Multiple Attacks or not. 6th ed doesn’t.
What about heroic campaign that mix the weapons and equipment bought with cash and some abilities (psionics, chi, magic…) with CP? Should they have access to Combined Attack if they didn’t buy it at a discount within a power framework?
Should monsters that bought their attacks (claws, bite, tail…) with CP, again not limited by PF, be allowed to Combined Attack?
The rules phrasing hint that GM should decide what is allowed or not. I’m fine with it as long as this is clearly set as ground rules for the campaign. It might affect point balance but players can choose to take advantage of it. Figuring all the edge cases can be a real headache. It can quickly go south when you have to make an on the spot ruling that affect the effectiveness of a player’s character. The more I think of it, I find it simpler to treat Combined Attack as Multiple attacks. Same penalties as if each power used is a separate attack, take a full phase, 1/2 DCV… Linked powers would require 2 separate to hit rolls. First the “carrier” attack and then the limited linked attack. This way, it stills act as a limitation.
Out of curiosity, how would you handle linked limitation if you don’t allow Combined and Multiple Attacks?