A Wall of Force must be continuous and broken when formed. If its surface is broken by any creature or object, the spell fails.Dreaddisease said:b] Why would you get a reflex save for something that forms AROUND you.[/b]
If there's the slightest indication of the wall's creation-- whether it's an audiovisual special effect like a Star Trek forcefield, or just a feeling of air movement-- the enclosed creature can have a chance to react. By extending a hand or weapon, or throwing a convenient rock into the plane of the spell, he could prevent it from forming and therefore avoid being trapped.
This isn't allowed by the book, mind you, since the spell as written has no save. But you asked how a save would make sense, and this is one possible explanation.
In terms of a single combat, the spell lasts effectively forever. Even the lowest-level caster gets 90 rounds of duration, which is long enough to fight a battle, heal the party's wounds, don a set of full plate armor, and then take a short nap.And it lasts 1 minute/level. I can't see why this would be such a bad thing.
...which means it's also a good way for the PCs to split their enemies and have an easier time. If the DM can use a tactic, the PCs can use it too. Anyway, I don't see how this is relevant to the spell's balance.Its a good way of splitting up the party and give them a harder challenge.