ccs
41st lv DM
I've never seen a skill check that was literally life or death,
I have. 2 sessions ago our bard walked out an open window - 10k feet directly above the pyramid we were raiding (1e module I3: Pharoh).
She thought the trick to reaching the floating funeral barge, anchored to a small cloud, was the walk of faith bit from Indiana Jones & the Last Crusade. Unlike Indy, she did NOT test this idea with a handful of gravel. Just walked straight out the window. The DM was kind & gave her a Dex save to catch the edge.
All of the other characters were busy doing stuff - looting, deciphering runes/clues, healing, two of us were having a serious in-character argument. Some in the same room, some in the adjacent room.
So the DM had us all roll initiative to see what order we'd all be responding in. The bard, hanging on by her fingertips, beat us all.
Rather than simply wait for the next person in order to come help, the 8str bard decided to make an athletics/climb check to pull herself back up & in.
The DM told her that this was not a good idea & that if she failed she'd remain hanging there BUT if she failed by 5 or more she'd plummet to her death.
She failed by way more than 5.
She dearly wished that she had taken the lucky feat.

And so our poor bard fell 10k feet & then rag-dolled down the side of the pyramid.
We gave her mangled remains a proper burial once the rest of us had escaped the tomb.