Some Setting Sun maneuvers are concentrated on throwing your target - Devastating Throw, Comet Throw etc, and some of them get even more throwing range than 10 ft. AND add some decent damage to that. But I've been thinking - can one increase the damage by throwing his enemy upwards? Like, even cutting 30 ft range in half should add some fall damage in addition to the direct one - if that works. So, how should the rules work in this case? Do we cut the distance in half, don't cut it at all, do something else?
Rules as written, can be a bit confusing.
Taking the strongest throw Comet Throw, we have the following wording:
First take the rules from Mighty Throw:
And add the rules for Comet Throw
It appears, that rules as written, if your DM allows places in the air to be "spaces", then you can choose a space which is over 10 feet from you in the air. For every 10 feet of space in the air, in which the target drops, it will take an additional d6 damage.
However, you have to might have to make sure that you throw it 5 feet horizontally before it is thrown five feet vertically, else the clause "it falls prone in it's current space" might takes affect and you don't get extra damage. Depending on if you read that rule as it's final destination space, or if you count the space vertically above you as it's own space.
Tome of Battle Makes Combat Better... and Sillier
Yes, when a maneuver says that the maneuver's target is moved away from the initiator, up is a valid direction away from the initiator. Most combat assume a closed environment, however, so clearance is a factor, and if the target can't be thrown into a clear space the target stays in its space.
The target might respond to the fall with immediate action if he's one available (i.e. he might've used it already; he was being attacked, after all). And, even if he does, finding a way to land safely without an epic Tumble skill check is challenging.
It's up to the DM if, as per the 1st-level Setting Sun maneuver mighty throw [strike], "[r]esolv[ing] the throw as a trip attempt" (ToB 73) is a trip attempt that actually trips. If so, according to the Rules Compendium, "A winged creature can be tripped, and if it is, it falls as if it didn’t maintain its minimum forward speed" (145), but the Rules Compendium is occasionally dubious (and, furthermore, not all flying creatures possess wings); I'd argue istead that a target the initiator launches into the air who possesses a fly speed and good or perfect maneuverability--therefore no minimum forward speed and can hover--is simply now in the air hovering (yet still technically prone) if the target doesn't want to fall, as that's more in keeping with the SRD. Nonflying creatures with worse than good maneuverability would drop 150 ft. immediately and 300 ft. each round on their turns until they hit--let's assume--the ground.
In other words, at low levels this is a valid tactic. And at high levels everyone flies anyway.
The Argument for a House Rule to Resolve the Fall on the Foe's Turn
Thus when a creature is launched into the air by a martial manuever, he stays there. He begins his turn, prone, in that midair square, and, when his turn ends--if he hasn't done anything about his situation--, then he falls. Not only is this hilarious, but it also gives the midair creature a chance to save himself from a potentially deadly fall, gives the midair creature an opportunity to act when he's probably not surrounded by the initiator's pals, and allows the midair creature--who might otherwise possess lousy maneuverability--to do something besides stupidly falling to his death even though he has frickin' wings.
This'd be exclusively for martial maneuvers, though. If, for example, some dude gets bull rushed off a cliff in a totally mundane way, he's on his own.
This might, in some corner cases, lead to absurdity (e.g. a creature falls off a 200 ft. cliff and the initiator takes a move action to leap after him, falls the 150 ft., catches up with the creature, and performs a strike on the creature that throws the creature in a deliberate effort to suspend the creature briefly in midair), but such cases are so weird that the chances are lightning strikes.
Some DMs might like this as it saves monsters; other DMs will hate it because it's silly.