Blood Ghoul
Sam went to the edge of the formation. Due to long term depletion of energy from the hydra, the formation has eroded.
But even after it was eroded, it is not easy for him to break.
His level of attainment in the formations and the inscriptions is not high enough for him to break the formation open
Even a stone wall which is tens of meters thick was tested with time and became as weak as a mud wall, digging a mud wall of that size isn't a normal person could do and Sam is in same situation.
But he didn't give up.
Sam thought about the energy flow in the formation and checked each and every spike. There are more than twenty chains which are acting as energy channels. There are a total of forty spikes out of which twenty of them are buried inside the earth acting as nodes.
He started observing all the nodes individually to where the formation is damaged causing these energy loop holes.