Was in The Vault (NIN) with a pretty iffy healer - for some reason she never used Medica II/ Regen/ DS, just spammed Cure II on the tank and then lost it when Charibert did his Knights -> Holy Chain -> Heavensflame x2 bit at the end. On our first/ second attempt the tank dies again, and the MNK is running around trying to keep Charibert busy while our healer resurrects the tank. Aha, I think to myself, 'tis time to use my NIN abilities and save the day! So I go to throw Smokebomb on the healer... only to derp in a truly magnificent manner and throw Smokebomb on the MNK and Shadewalker on the WHM, killing us all.

Afterwards:
MNK: We were so close!
Me: Yeah... just don't know what happened there.