terrainmonkey said:
first of all, the party should not have seen the dragon at all, as he should have been invisible. 2nd, the dragon has blindsense, and other abilities that are constantly on that detect magic and see arcane energy. so, the dragon wouldn't even give them a chance to get off a spell before he attacked. you have to understand the dragon's age. most dragons are not stupid when they see some group of adventuring yahoos. they will see them before the party sees the dragon, then he will go invisible, then he will cast silence 15' radius, and then go hover over the party and flame breath. then he'll come down on the party thief or cleric and tear them apart, then move on to the wizard so he doesn't have to worry about the spellcaster even thinking wall of force. dragons are not going to fall for the "flying into the wall of force trick". besides, even if he did get the wall up, and if the dragon did actually hit the wall, no damage would be done to the dragon and the wall would fall over or break apart. this is a lame, non damaging tactic, and not something an intelligent mage would do. there are far more damaging spells than a wall of force.
You must be reading a different starting scenario in the original post and a different set of rules books than the rest of us. The reason an intelligent mage would do this is to 1) temporarily limit the mobility of the Dragon and 2) avoid the Spell Resistance of the Dragon. I think it is a very good tactic. Maybe the people who play "intelligent wizards" in your game only throw damaging spells.
It is unlikely that Good Dragons would attack travelers. Hence, we are typically talking an Evil Dragon here. An Evil Dragon usable against a mid-level party would be maybe an Adult Black (int 12), a Young Adult Blue (int 14), an Adult Green (int 16), a Juvenile Red (int 14), or an Adult White (int 10).
Although smart, none of these dragons will typically be as intelligent as a party Wizard at that level. So, they should not be tactical geniuses in combat.
Also, this type of dragon will be young and cocky. They are not as smart as older wyrms who have figured out that you can get killed attacking adventurers. You don't attack them smart, you just do not attack them at all (or use minions).
Hence, younger cockier dragons will not go in all prepped. They will rely on their massive combat abilities and might cast a defensive spell or two. Who knows, they may need to save some of their spells for possible later encounters in the day. Only when they determine that they may be outmatched or minimally at least challenged will they thrown in the kitchen sink.
Plus, blindsense only has a range of 60 feet. It does not mean that a dragon will automatically spot his enemies at 500 feet (the original scenario) before they spot him. That's why we roll Spot Checks in the game.
If I had a DM who had 10 to 16 Int Dragons ALWAYS spotting us first and ALWAYS having just the right combination of powers to defeat us (most Dragons should not have Clerical spells at all, let alone Silence; Invisibility only lasts 1 minute per level, so WHY would a Dragon just happen to be flying around with it one?, etc.), I would go look for a new DM. An encounter should be a challenge, but the enemies should not be totally prepped, nearly omnipotent and genius level intelligent like you made your dragon out to be.
Finally, Walls of Force never break and never fall over. I would also get a new DM if his Dragon slammed into a Wall of Force at 300 feet per round and took no damage. If anything is lame, it is a hidebound DM who cannot reasonably adapt to an unusual situation and reward players for coming up with interesting non-conventional tactics.
PS. It is reasonable, however, to make any damage from the wall non-lethal damage.