(Un?)Ethical Question (hypothetical)
Background first to explain how the game is going and what my players expectation are. (TLDR at the end)
I've been doing my writing for my homebrew campaign and we are about a year in IRL (2 6-8 hour sessions a month). I'm somewhat railroad-y with the game as my players and I both enjoy the story aspect of it more than the sandbox vibe, although I always write about 3 branched paths for their mid to large choices. I do have the cliche boblin the goblin that the party has grown quite fond of as well. My campaign is pretty dark and heavy for the main theme but he's been some great comedic relief but the idea i have for rounding out the finale of ACT one is having him sacrifice himself to save the party and solidify the party's purpose and commitment to the next step, show them the world does have consequences and the story is bigger than just a ragtag group.
Anyway, I have the encounter set up with a homebrewed monster that can paralyze as a shriek that gets stronger and stronger as the fight progresses, eventually requiring high DC checks to pass. My idea is that boblin will figure out how to overcome it (he's an artificer with 6 INT btw) and break out of it.
My idea was to buy a loaded d20 unbeknownst to my players and open roll the final roll for him to save if they all failed and he would basically blow himself up to save the party. I opted not to due to the variables with this, and i know if they found out it could be problematic with the game but we are a more story themed group.
TLDR: I was wondering what others thoughts are on rolling a load d20 in the open to make a final moment seem so epic for the players, and what alternatives could happen to ethically take away some "fairness" to the game while still making it an intense moment for the players?