The Avatar of Babi wreak the most havoc as his attacks would sends shockwaves that would cleave the sands. If the ground itself was not made of sand, then it might have cracked open by the sheer force of his attacks. He easily bashed any player that does not have great footing into the sands below their feet.
The players that were already accustomed to hard ground had difficulty in maintaining their balance. This is true for the tank players as they need solid ground to stabilize their footing compared to other classes. They need to absorb the energy and shock from the attacks of enemies then distribute it to the ground below them.
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