Originally Posted by
Sservis
It's still a personal preference thing through TH9 if you war, through TH11 probably if you don't. As long as you have some defense, you'll get shields, 30% is a pretty low bar, you just need to force the attacker to use enough troops. The odds you get full attacked are much higher though so retention will be somewhat worse.
Clan war wise, TH9 is an easier 3 star for good players with the extra time and DE spell. This means that defenses don't really matter at TH9 and below for clan wars as long as you can attack for 3 stars on your own TH level. Th10 is a different story for clan wars and in a bad place both maxed and rushed right now. (TH11 3 stars max TH10, but max TH10 has trouble 3 starring weak TH10s, so why bring TH10s to wars again?)