"authority to trample on snakes and crush scorpions." Possible meanings are 1) snakes and scorpions are a metaphor for evil spirits. Alternate translation: "the right to defeat evil spirits" or 2) this refers to actual snakes and scorpions. (See: [[rc://en/ta/man/jit/figs-metaphor]])
This implies that they would do this and not be injured. Alternate translation: "walk on snakes and scorpions, which will not hurt you," (See: [[rc://en/ta/man/jit/figs-explicit]])
"I have given you authority to crush the power of the enemy" or "I have given you authority to defeat the enemy." The enemy is Satan. (See: [[rc://en/ta/man/jit/figs-ellipsis]] and [[rc://en/ta/man/jit/figs-explicit]])