And this Int 2 animal gives the druid exact direction and GPS coordinates? But the animal first has to swim all the way from the dragon to the druid who is very far away in safety.
How likely is that?
Very. Something like coming across a dragon rates up there on list of memorable events for a normal critter. Granted, the Int 2 creature isn't going to tell you that it's X hundred feet north, or Y miles west, but it can easily tell you that yes, I saw it over in
that direction, a little ways from the Local Identifying Feature. Heh, don't handwave off Int 2 creatures; sure they won't do calculus, but Lassie was Int 2 after all.
And that's not even touching on Commune With Nature. Fact is the druid can find the dragon.
if the dragon is finished with its rage, the swamp is barren.
If the dragon razes the swamp, it's not planning on sticking around and living there any longer. Razed swampland quickly becomes a really crappy home - oh look, you're constantly exposed, food is scarce now because you've destroyed the ecosystem and you're constantly open to the elements. A pretty dang far cry from comfortable. Or even tolerable.
Not even to touch on the "Dragon living in a swamp, One druid's problem. Dragon destroyed a swamp, Many druids' problem." issue. How To Make Your Problems Worse 101.
The druid has to sleep somewhere. Despite all the nature abilities, druids are as fragile as other humans when it comes to weather. Heat, Cold, all harms the druid. He needs a fire to cook his meals (or does a swamp has many berries for the druid to eat even before he got venom imunity?). Also druids have no divine health so unless he wants to cast remove disease after every heavy rain he better has a dwelling where he'd spend the levels before he could cast 3rd level spells.
Also his equipment will also suffer when constantly exposed to the swamp.
Yes, he does to sleep somewhere. And at 10th level he can do all his sleeping in the form of an indigenous animal thanks to Wild Shape. Like as a snake in a tree somewhere. Pretty inconspicuous if you ask me. As for heat and cold - the swamp isn't going to have heat/cold that's damaging, and if the druid's lived there for a while he's probably quite acclimatized to it.
Food isn't that big an issue to a druid. Long-term animal friends that help him out, his companion, goodberry, purify food and drink, hunting while wildshaped, etc. etc. How or what he ate before 10th level is of absolutly no relevance whatsoever, though. Doesn't matter how he did it, he just did it and survived long enough to get to 10th level.
Why would he have to cast Remove Disease after every heavy rainfall? So he doesn't catch the sniffles? Again, acclimatized. Minor environmental annoyances do not bother him if he's been living there for a good ammount of time.
As for equipment - screw equipment. Equipment hasn't even entered into the picture before this point, and it has no need to now. 99.9% of any equipment the druid would possibly need he can get from, or create out of nature. Part of the whole druid schtick is that a druid is not overly reliant on stuff to do his thing.
The whole fight depends (as always in D&D) on the equipment. If the dragon has some good anti magic items, the druid has a serious problem.
What kind of equipment? Keeping in mind that the dragon has triple standard treasure for a CR 10 encounter, or a grand total of 17400 gold available to him. And there's no reasonable way that it's going to all be in anti-druid related magic items.
A real cunning dragon might, when he can hit the druid one times, sunder the misteltoe.
He might, if he gets into melee. But part of the whole idea is to not melee directly with the giant rampaging armored engine of destruction. In melee they tend to do things like... win. Besides as I've said at my own table many times in the past, any divine caster that carries only one focus on them deserves what they get.
What action is it to transport from one tree to another? If it takes a action the druid runs the risk that the dragon destroys the tree while he is inside, instantly killing the druid. (Or the dragon might ready an action for it)
It's a full round action to jump, tree to tree. But the chances that the tree is at risk are low, again working off the Dragon In Melee = Bad model.
Generally the way it would be set up is as so: Druid gets the drop on the dragon, with Tree Stride already in effect and ready for use. Druid casts Wall of Thorns, trapping the dragon. The dragon can attempt to struggle free by taking a full-round action and succeeding at a DC25 strength check, which with a Str of 23, it only makes on an 18-20. The dragon's breath weapon does not affect the wall in any way, as it is not an edged weapon or magical fire. Druid then casts Baleful Polymorph, and if it doesn't work steps into a tree with his move action. Dragon can attempt to struggle free again, or if it succeeded the first time around, move toward the area where it thinks the druid is. Assuming it has any idea where the druid was when he cast the spell - it may not, taking into account things like size, cover, distance and the fact that the druid may well have been an animal at the time. Charging is not an option (obstacles), and even if it were wouldn't get the dragon far enough to attack the tree it thinks the druid is in (120' total charge distance vs estimated 200' casting distance). Flying is not an option due to close terrain. Dragon can take the Run action to get to the tree, again assuming it knows which one is the right one, but is then out of actions and cannot attack it. Druid then Tree Strides and is gone.
