Control Weather.

[Tubben]

In a while we will do some castle siege.

My group will defend the castle vs. an unknown number of attackers.

My party is 20+ and we will have other players taking part of the "npc" army. They will play some higher lv npc and their vassals.

I play an moon druid and was thinking how to do my part. Since i dont know yet, what we will fight against (small pack of high lv, large pack of low-mid lv - i dont know), i was thinking to do an control weather.

Unfortunally the rules for control weather vs npc are not there.

any ideas (maybe using others spells as an benchmark) if you run into an area with "torrential rain, driving hail or blizzard" + "arctic cold" + "storm".

Given the 5 miles radius it could help to decimate the attacker before they reach us ;P

[Sigreid]

What you're looking for is the write up on weather in the exploration section of the rules.

Dont forget to use your ability to cast while shifted into something hard to spot to destroy their supplies and shelter.

[Lord8Ball]

If there are mountains around you would try to freeze the earth with cold weather and then heat it up causing floods and mudslides. For flat ground try making it difficult terrain by putting torrential downfall and then freezing it and adding hail as an added measure. Also, you could try doing rainfall then freeze over and over to try and make advantageous terrain. I am not sure if this is within the limits of the spell since I don't have it on me atm.

[Sigreid]

Remember, castles are built because you dont have to defeat the invaders. You just have to keep them outside until they are uncomfortable and hungry enough that they have to leave.

Freezing cold one day. Boiling hot the next. Maybe hot and muggy for a few days. Just make it miserable as hell for the people who dont have shelter.