As an addendum, I'll echo the sentiment of not a fan of the "but magic" having to legitimize all of the various effects of Legendary Creatures. One of my primary beefs with 3.x at the end of my tenure running 2 extremely long campaigns (that spanned epic in both) was that BBEGs were absolutely 0 threat to PCs unless a "but magic" template or class was used; eg dragons had to be played as giant lizard sorcerers to pose the requisite threat to epic heroes. Relevant, threatening, mundane BBEG was well outside of the scope of play by level 10. That needs to not happen again.
I partially disagree.
One the one hand, I like the idea that legendary creatures can break the rules, and thus gain access to some of the design principles that 4e developed for solo creatures. I had some really satisfying fights with well designed solo enemies in 4e, and I would like to continue using that technology for D&DN.
Further, I also like the legendary/solo break in 4e, where creatures get to break the rules because they are extraordinary, and not merely because the game mechanics need to adjust in order to make a much higher level enemy fun for lower level PCs to fight. The idea that the same "mid-to-high level fighter" could be a solo for a low-level party, an elite for a mid-level party and a standard creature for a high level party has some significant downsides. Partially, it seriously offends the sensibilities of the folks who believe that the rules should be consistent regardless of the level of PCs that turn up. And, partially, even if you aren't offended, it's much easier to manage the game if a given creature always has the same stats.
In other words, there are real benefits to limiting "game breaking" to a legendary class of creatures and items.
But I also partially agree with you. It would be nice if you could have a satisfying big fight with a single enemy without resorting to legendary foes.
With flat math, a hill giant is a fair tough fight for a party of 3rd level characters, but a couple failed saves against grease spells and a party with good ranged attacks could have an easy fight. To some degree, that's ok. If the answer is that encounters against powerful non-legendary creatures are swingy and could end quickly if the monster has a bad save or two, I guess that's ok if DMs have the legendary tool in their pocket.
But I sometimes wonder if flat math has gone a little too far, and what D&DN needs isn't flat math, but just "flatter" math. A small save bonus to high level monsters (or the like) might generate more satisfying fights against foes of substantially different levels? I'm not sure. How many folks have spent a lot of time testing out those kind of encounters?
-KS
