You have a good start but it seems like it may be overpowered, since the upgrade to the spell factory would make this new spell also come with the capacity for one more spell for a total of 6 spells. If the duration starts off at 10 seconds you could use 6 of these for a total of 60 seconds. So perhaps what you have is 2 spell ideas (one being damage reduction to fire powered defences and the other being something that sends away heros and clan castle troops for a little while.)
As far as the damage reduction goes you can kinda consider the heal spell as cancelling out a certain amount of damage but from all defences not just the "fire Powered" ones. Which would make the heal spell seem more likely to be actually used. And the freeze spell stops all defences in the affected area for a short time so that would seem more practical to use.
A base wide effect wouldn't be necessary since there is no need to attack a base from all sides unless your barchering but in that case you are trying to spend as little as possible and for the duration it would not be cost effective. In The case of an all Drag or all Balloon attack this spell would be of little value. So the only scenario I see the basewide effect to be really utilized is an all hog attack which was already so ridiculously effective that Supercell had to take action to balance the hogs out with more damage from giant bombs.
The part that I really like is the ability to send heros and clan troops away. I think they should go to the clan castle not to the Town Hall. As per the description of the clan castle once you destroy it the troops become trapped inside but has anyone really pulled this off effectively? I have never been able to destroy the clan castle before all the troops are released (If anyone is able to do this effectively please share how!) The spell should just be an area effect that gets dropped on the heros or clan troops. While inside the clan castle the Heros and clan castle troops should regenerate their health at a specified rate so repeated use of this spell means everyone comes out recharged and ready for battle. When the time limit is up the heros and clan troops exit the clan castle all together allowing for easier repeat spell uses.
As for using the environment to change an aspect of the offences or defences during an attack, its a really great idea but that seems like it would require its own category and since every base has the same environment maybe that idea could come with the option to chose aspects of your environment (for example your clan resides in the shoreline area and someone else's clan could reside in the forest or maybe mountainous region) But this really seems like a lot to add in to an app. from a graphic and programming stand point.

