Back in 2005, on the occasion of my 33rd birthday, I ran a session of White Plume Mountain using AD&D rules for my friends, and this unusual interaction of the haste spell came into play.
The full report is
here, but I excerpt the relevant text:
Ben then decides to even the odds with a haste spell. He’s used to how it works in 3e. It looks pretty similar in 1e, doesn’t it?
If you want a spell that is obscure in full effect, it’s hard to go past the 1e haste spell. The text of the spell notes that it ages those under its effect. The DMG notes that the aging is 1 year. The PHB’s Constitution table notes that those who magically age must make a System Shock check or die.
This was something of a surprise to Ben when I explained the effect… and Mat and Blake both failed their System Shock checks. (Ben failed as well, but I’d ruled he wasn’t in the area of effect; a mistake I note when looking at the spell description now. It’s meant to be centred on the caster. Oh, well).
About ten minutes later, when the laughter had subsided (Ben: “I did what?”), Sarah eventually managed to slay the Slayer. (I just wanted to say that). Ben and Sarah looked around at the bodies, and decided to get out of the dungeon and to a nearby town to rest up and recruit new companions.