Strategic Diversity: Allowing Attackers to Substitute Different Troops/Spells

You could allow people to build reserves for a limited housing space (at least 50 housing space). Same goes for spells. In the half minute prior to the attack, the attacker can then substitute their reserves with their main line up. This will allow the attacker to hit more bases and hit next fewer times.

For example, a farmer might gibarch in order to profit, but then he comes across a th10 with 600k+ each, which he would like to attack, but his troop composition/spells aren't strong enough for that sort of base. He can then switch to a comp that has golems wizards and freeze spells.

I also realize this could be a huge pain in the *** from a development standpoint. Maybe if it is too difficult to do it for troops, it could at least be done with spells.