I've been trying to place this story for a while now so hoping someone can help.
Setting: Fantasy, various main characters have elemental themed magical abilities (one has fire magic, another water etc)
Main plot points: A sleight of hand magician/entertainer is hired to pretend to be a prince(?) who has fire magic. I can't remember if this is a decoy situation or if the original is missing. I remember there was a lot of conflict between the characters factions including assassinations attempts (see below).
Memorable scenes: I distinctly recall one scene where the main character was in his rooms and one of the other characters tried to kill him by summoning a globe of water around his head to drown him. He was able to escape by using a tube/straw to breathe.
There was a ritual that needed to be performed by putting the persons blood onto a stone, the people who had hired the main character were worried about this but he dismissed their concerns by explaining he would have a vial of blood up his sleeve and pull the cork with some string.
I think there was a character in the book who was a bodyguard and the highest ranked duellist in the kingdom, but fought with a great axe (though I may be confusing an entirely different story here)
Other details: This was an English language book (not translated that I recall), that I'm fairly sure I read at least 15 years ago.