[Surrealistik]

Originally Posted by fallenwarrior

I'm not sure you need to limit no action effects the same way. Could you give me an example where that would be necessary, given the above house rule?

I'm aware of the limitation on free action attacks. My concern is with, as a solitary example, unlimited free action item swapping via the Disembodied Hand/Rakshasa familiars (which is not subject to the attack limitation). This can be problematic in that a player can receive a disproportionate benefit from a lot of cheap but cumulatively very powerful items (Staff of Aversion, Orbs of Nimble Thought, Orbs of Mental Constitution, etc).

As for problems with no action attacks, some examples from the Handbook of Broken:

Spam of Kings

Spoiler

The Sword of Kings feature of Legendary Sovereign assumes that all weapon encounter attack powers have attack rolls. Power Strike (or some of the attack power Subs from the Iron Warrior theme) would beg to differ. You never attack: therefore you can't miss. So infinitely use one power on a hit.

Scion of World Ending

Spoiler

Scion of Sacrifice has a level 16 feature to allow you to use an at-will power whenever you drop below zero. You know that's gonna be trouble. Attack yourself (Throw and Stab, or various AoE at-will powers have been suggested), have enough resistance that you will kill yourself very very slowly, some way of healing regularly (like a staff that heals you when you kill a monster), add something else to move around a lot (Mobile Warrior), and destroy the world.

Bag of Rats can be argued to address this however.

Doing damage to yourself doesn't count for recharging powers or generating attacks (unless that is specifically an effect of the power you are using).

You can rules lawyer this into oblivion with existing restrictions by citing the 'Bag of Rats' rule from the DMG, P40:

Originally Posted by DMG P40

When a power has an effect that occurs upon hitting a target—or reducing a target to 0 hit points—the power functions only when the target in question is a meaningful threat. Characters can gain no benefit from carrying a sack of rats in hopes of healing their allies by hitting the rats.

Originally Posted by fallenwarrior

Vulnerabilities only trigger 1/turn

This one is controversial, but I think it's necessary given how many people are using attack powers which allow more than one attack per round (eg, Twin Strike). The basic idea is similar to your rule #4.

I'm not sure whether I'd call this one 'essential', in that the rule doesn't address a fundamental design/scaling flaw or prevent something from bending/breaking the game. Multiple exploitation of vulnerabilities is certainly powerful, and can be cheesy, but it's rarely if ever a show stopper.