By the rules, inspiration can only be used if announced before the roll (although the DMG recommends allowing using it after the roll for more heroic campaigns). We play it being used before the roll, the campaign is more on the gritty side, with lingering injuries from failed death saves.
In yesterday's game, one of the players failed his second death save with a natural 1, which would have instantly have killed his character. After scalding his compatriots for not healing him earlier as requested, the players asked if they could use their inspiration on the roll in arrears? Nope, need to do this before the roll. Then, the players asked if they could do it if they spent two uses of inspiration on the roll (two of them still had it). Because this was a real cost they were willing to take and because it helped keep the game flowing, I said yes, the roll was rerolled, death avoided, and everyone was happy.
This actually worked so well that I wonder if this should be a standing house rule.
- You have to pay a double the cost and there need to be at least two party members that have inspiration. It will likely only be used to avoid dire outcomes.
- On the other hand, it saves you spending uses on rolls that are only important in case they fail catastrophically - you can just wait on the result and only spend it if needed. So if this was used as a general rule, over time it might actually be cheaper than using normal inspiration.
- It is less of a freebie boost than the DMG-proposed alternative of just allowing it always.
Is there anyone who has done this before as a regular rule, and who can can offer an experience based answer of how this plays? Alternatively, experiences with allowing inspiration after the roll would be helpful, too.