Increase Tail Lash’s damage by 2d8 to 4d8+12 damage. Add “Special: While Orcus is bloodied, Tail Lash becomes a minor action, usable once a round (it’s no longer an immediate reaction).”
I like this change, but it also reminds me of another factor which has been irritating me for quite some time now - namely that Orcus makes very poor use of the action economy, since he has no swift action abilities available to him!
This means that every round, he attacks once, then moves, even if it may not necessarily be in his best interests to move. At least with an at-will swift power, he can use it 1/round, and maybe convert his move to another swift if he does not need to move.
I think it may be better to convert his tail lash to a swift action ability usable at all times. He still retains the ability to lash out with it as an immediate action, and designate another ability while bloodied (or the ability to lash out could be his bloodied ability).
Though personally, I would prefer for him to have 1 move, 1 standard, 1 swift and 1 interrupt ability, so he can maximize his action quota for the each round.
Compare this with demogorgon, who gets to move into a choice square, attack with 2 standard-action powers, follow up with 2 swift-action powers, potentially 1 more with action point, then move away. He clearly makes much more efficient use of the actions allotted to him.