...Can you please post stories of ALL the character deaths in your game so far? They're freaking hilarious!
I agree that the players sound hopelessly dense. However, let's assume the opposite. Let's assume krupintupple portrayed the stories in a way that minimizes his culpability. Maybe some critique from that perspective will help krupintupple to see ways to aid the players in future circumstances.
Fighter finds a Red Tiger (Forgotten Realms) which is a CR7 lion and attempts to solo it.
This could be the player's fault, certainly. However, did you (krupintupple) describe the lion properly? I mean, a 3rd level character might think that he
could solo a lion, if he doesn't know anything about a lion's stats. Then on top of that it's a more-powerful-than-normal lion. So, did you explain this? I mean, something simple like this should suffice: "The beast is menacing, dangerous, with a hungry look in its eye. Even with your weapon drawn, the creature is undaunted. You get the strange feeling that he views you less as a person and more as food."
the rogue decides to stay back to "ensure that no undead came out during the night"; party thinks he's crazy and leave him. rogue tries to sneak back in to get some loot. with no reliable way to deal with shadows and a Str of 9, he didn't really last long.
Hey, maybe the shadows hadn't done a lot of strength draining while the characters were there as a team. So of course the rogue would assume that there would be very little strength draining! I mean, we
just don't know what went down before the rogue... went down.
(Yeah, OK, I'm stretching it here. This one is hard to defend.)
Dwarf jumps off 250' gorge and attempts to use wand of featherfall. I explain to him that unless he has it on his list, he can't use it. He's a Fighter and plummets to his death.
Wait. You explained it to him and
still had the character fall to his death? I'm in the habit of explaining game mechanics and then letting players rethink. You could say, "OK, so you know that you need to be a spellcaster to activate that wand. You sure?" And if the player says, "Not sure, can I take it back?" then the DM says YES.
In addition, maybe the fighter had UMD. Did you at least give him a roll?
Character dies while trying to grapple a shark with a "I saw it on TV" maneuvre.
While it was good of you to explain that game mechanics don't mirror TV, if the character had a decent explanation of what he or she was doing, and it seemed to be based off some real-world logic, then I think you owe it to the player to reward such smarts with a +2 circumstance bonus. Maybe it would have made the difference if you'd played along a little bit.
The then 4 PCs are wandering through the woods and hear drumming and chanting and come across barbarians. They're wildmen, like vikings, but friendly-looking. One notices the PCs and approaches, hand out and unarmed. They kill him.
Let's play this out.
DM: You come across some chanting barbarians. One sees you and approaches.
Player: Oh, crap. Can I get a swing in? Are we in initiative? Does he have surprise?
DM: Really? Damnit. Fine, you get in a swing, and he's dead. He was unarmed, unarmored, and had his hand out in a gesture of friendship, you idiot!
Of course, telling the players how friendly the barbarian was after they've already done the killing is useless. The DM needs to describe the scenarios up front.
(One should note that almost all my rebuttals were made tongue in cheek. However, if krupintupple really
did present these 5 character deaths in such a way as to make the players look dumber than they were, I'd hope that maybe even my goofy responses provide food for thought.)