Showing my interest here, I will try to get up a cs tonight.

@Renny. If you want I might have a solution for your jutsu. Note that I am just throwing a idea out, up to you what your do with it.

What you can do have 2 versions of mercury. First of is the gaseous form (normally it would take heat of around 220 degrees Celsius for this, but woot for chakra to convert it to that :D), the vapor itself is highly toxic if breathed in. A small dose could lead to nausea, loss of balance/equilibrium, memory loss, etc. Large doses can effect the nerve system and lead to organ failure. In game terms I would think 1 round of exposure small impairment to fighting ability, second round major impairment, third severe impairment/almost unable to act due to pain and other effects, fourth round is death. Although after the second d and third round you will need medical attention within a reasonable time.

Second is the solid form, mercury has a melting point of -39 degrees Celsius, meaning only really cold temperatures can freeze it. What you could do instead is have it bind with a different metal (zinc, silver and gold are common variants). This would form a amalgam, which isn't toxic. Atleast not for combat purposes, but it could easily be formed and used without dangers for your character. For example you could use earth chakra to add iron and carbon to the mercury compound, which could make a weapon as strong as iron (roughly).

Like Unsaid before it's just a idea. And if you want I could expand my explanation, when I am not at work and on my phone :D.