Maitre' D Yeti:
You want to know how to use the item you got from me?

Bring some Hot Spring Nectar to the Yeti, they'll use it on their jackpot to make it grow faster. Otherwise, Hot Spring Mineral Water will aid the growth of your jackpot, but inhibit the growth of the other's.
If you bring Hot Spring Dragon Water to the maitre' d, he'll secretly exchange your jackpot with the opposing team's and with Hot Spring Sulfur, you can put all the others' arenas on debuff.