Now that would vary depend on what i was trying to achieve. If i wanted to make it harder for them to escape, i'd say the it spread to mid range all around them with myself on the outside. I would go on to say due to is runny consistancy you'd sink up to your waist as it forms and that it's 20m deep so that you can't just use an earthen pillar. If i wanted to be really picky, i'd say if hit with wind such as hurricane fist it would splash the mud up rather than push you out of the swamp.*noted* ahead of them, use first Jutsu's weakness as a second attack. and Sensei what will be the ideal description of the swamp according to you?
But like i say it depends on how you want to play it. Description is everything, assess the situation, evaluate what you're up against, decide where you want your opponent and force them into that situation.