The main problem with undine and sylph industry is that it's boring. That
aside, the game reason it won't work is turbulence. A sylph is not a window
fan. It's a whirlwind. Harness the wind, indeed. Pshaw. Likewise,
undines reflect the elemental uncontrollability of water, and the longer you
try to control one the harder it gets. The effect for both elementals is
not as noticeable in the short run. BTW, riding a sylph is kinda bumpy.
CON x10 the first round, with the multiple being reduced by 1 each round to
a minimum of 1 to avoid tossing your cookies.