You say your group is fine w/ your "house rule" and that they don't know that you "house rule" it. Obviously they will be fine with it if they assume the rule is RAW. (Of course, there are people that argue about RAW)
At least the hydra has a choice - a lot of powers _have_ to be multiple targets, and those are where I think RAW falls down the most.
That and I think a lot of players would be shocked if they got marked and did an Icy Rays (or similar multitargeting ranged attack) and then got smacked by the monster that marked them. 'But I included them in the attack!' 'Well, yeah, but not in the attack on him.' 'But, it's the same attack, Icy Rays' 'No, no, it's a different attack as part of the same power' '... what?'
I totally agree with you, those damn demigods how dare they use their puny powers and class features against the DMs almighty gods - not.But I'm ok with that. When the PCs finally meet Tiamat, there is no way that the Fighter is going to be able to lock her down like that and automatically get a free Combat Challenge every single round.
I'm inclined to say that if a power specifies that it must be multi target (eg icy rays etc) to treat it as one attack for marking, if the creature can choose targets for each seperate attack (eg hydra) the mark applies to each one.
Furthermore, if you use ranged attacks while in melee you deserve getting smacked
Never said it was in melee. There are things like:
Divine Challenge (minor, at-will)
Necrotic![]()
Ranged 5; the target is marked until the death knight uses this power against another target. If the target makes an attack that doesn’t include the death knight as a target, the target takes a -2 penalty to attack rolls and 15 necrotic damage.