The block above might only last 5 rounds.
A simpler setup is 64E, 136C, which lasts a minimum of 6 rounds and an average of 8. Leaves plenty of time for the main attack.
Also, if you're counting flags, you want the attack to be following just over 6 flags behind the block.
Finally, if you're trying your own simulations on the shaman camp, note that the simulator currently has the wrong data - it's a factor of 10 out on the shaman's HP...