A reliable way to practice war attacks.
I'd say most people are in want of a means to reliably practice war attacks. Practicing an attack you are not used to during the actual war makes you a liability for you clan, because you will most likely screw it up. And practicing in normal matchmaking works to a certain attack, as you can work on deployment and timing, but only having 30 seconds of planning makes this unreliable, plus there is no way to customize your army for a base, you just have to make a cookie-cutter army and hope you find a base it works on.
The most common idea I've seen for this is to practice on a clanmate's base, or practice on your own base. Now, as most of us know this just won't work. It's too easily exploitable, as you can copy an enemies war base, or someone you are planning on revenging, and practice away.
My idea is to add, perhaps on the single player map, a daily or weekly base that we can practice on. This base would be scaled to your town hall level, and would be realistically designed. By realistically, I pretty much mean it has the same amount of buildings as the town hall it is at and levels for those buildings that match the town hall level. This is what makes the goblin maps so unreliable to practice on. Pekka's playhouse has like 8 teslas or something, and its just unrealistic. Same with Dr Terror on BB. The daily/weekly base would also have a layout that is realistic to something you may find in war, all regulated by SC of course, so they could choose to give a popular internet base to practice on or just a layout that looks reasonably challenging.
To go into further detail these daily practice bases would be the same for everyone at that th level. So for example all the th8s would get the same base, all the th9 would get the same base, etc. You would be able to share the attacks you make on the bases with clanmates to compare the best ways of attacking it, and give tips to struggling clanmates by showing your own attack.
There would be no resource reward for this, and no cost of the troops you use would get refunded, so you would have to be thrifty with your attacks. The only motivation for this would be to practice a war attack or any attack you want really.
I think this would be a great feature to add. I personally and trying to get better with hog attacks, but I don't want to do it during war, because I don't want to have a crappy 1 star attack and bring my clan down. And of course 30 seconds for planning in regular matchmaking is just not enough time for a well executed attack.