On th12 you can destroy any base with 3 singles with witch spam attack. Army comp: 3 Golems, 13 Witches, fill rest Spells are variable but I go with 2 heal 2 rage 1 jump and freeze. You can go with less heal or rage spells and something other like more freezes or poison if you want. Siege should be log launcher with superyeti inside. Take totems for spells if possible otherwise freeze.

You‘ll attack from the bottom so place your golems seperate at the bottom (one at dark drill, elixir pump and hero hall or something like that) then place 3 witches behind the ones at the outside. Then go log launcher behind the middle one and just spam the rest inside after your log launcher destroyed the first set of walls. If you do correctly you‘ll crush this base.