I'm playing my first solo game that I plan to finish now and I discarded all the cards in hand (hypothetical other player) from one hero to destroy the Toxic Seaweed environment card. Now this hero doesn't have a hand of cards. Then the next villain card that was played was Baron Blade's "Consider The Price of Victory makes each player discard 1 card...but one of my heroes (the one that destroyed Toxic Seaweed) doesn't have a hand of cards.
what happens next? Does that hero immediately draw 4 cards after discarding hand? Or does she (The Wraith) continue to play the game without a regular hand; depending entirely on drawing cards from the draw phase and abilties that allow card drawing?
You stay with no hand. If something tells you to discard a card (like Consider the Price), you just cant discard since you have no cards to discard. I think Consider the Price does more damage if less cards are discarded that way (and this is why)
Also, keep in mind that if you do not play a card and use a power during one turn, you may draw an extra card in your draw phase. So if your Wraith has no hand, an option is to skip playing a card and skip using a power to draw 2 cards.
If you have no cards in-hand and something tells you to discard, then you can't discard. So if "Consider the Price of Victory!" comes out there's a player with no cards, that's one less card that's going to be discarded. The only way to draw new cards is during your Draw phase (note - this is optional, as you never have to play/power/draw during those phases of your turn) or if some other effect says you can. At no point do you ever automatically draw a card for no reason. There is also no maximum hand - you could have your entire deck in-hand if the game went on long enough and you never played or discarded anything. I've certainly played at least one game (possibly two, both as the Adept) where I had my entire deck out (not all cards were in-hand, though - some were in play).
Note also that if something tells you you can "discard your hand" to do something (like Toxic Seaweed), a hand of zero cards is still a hand, so you can still "discard" it :).
It has, however, been ruled that an Incapacitated hero no longer has a hand at all, and thus they cannot discard their hand. They can skip their turn, though…their turn normally consists of using one of their incap abilities, but they can give that up to delay a Self-Destruct Sequence or the like.
That's true - I wasn't thinking of Incapped heroes, just active ones, but yeah, incapped heroes have no cards except their character card (which doesn't count) and so their turn becomes Start phase, Incapped Ability phase, End phase. The only time they don't get this is if playing in the FInal Wasteland and killed by an environment target while Unforgiving Wasteland is out. But that's true of anything destroyed in such a manner (though "destroyed" is the wrong word as stuff which gets "eaten" like that explicitly isn't destroyed, which is why having the Final Wasteland eat all of Lilian's Fowl is so much fun >:)).