Shen repeated the same action, avoiding the dust storm, and waited for [Frozen Spear]'s cooldown before he attacked the rolling monster. Tedious and repetitive, but it was a safer choice for him since he did not know yet what this rolling creature was capable of.
However, he soon realized the issue of his strategy that relied on [Frozen Spear]. His total mana was two hundred and sixty, and [Frozen Spear]'s mana cost was ninety. That meant he could only use [Frozen Spear] two times, and he realized that when he tried to cast [Frozen Spear] for the third time. He only had eighty-seven mana left, three more mana to cast the third [Frozen Spear].
The moment he realized that was when the rolling monster was three meters in front of him. He thought of using [Frozen Spear] as close as possible so he would have more time to hit the monster instead of following the [Frozen Spear]. But the plan backfired because he did not properly check how much mana he had.
