Has anyone tried this one? I think it might make a cool tornado effect.
http://m.dhgate.com/product/two-function-10-inches-new-tornado-perk-water/214224562.html#pd-019
Tornado percs are not great at creating a tornado effect with vaporizers - they require a stronger pull to give it a twisting motion. It's been said before that those style percs are best used as splashguards in addition to a better perc.
If you're dabbing, it might be fine, but I don't really see the value of those percs. If you want a vortexing water action, might want to look at a recycler instead