You have authority over demons, because Jesus has triumphed over the devil.

“Then the seventy returned with joy [chara], saying, Lord, even the demons are subject to us in Your name.” (Lk 10:17)

“Behold, I give you the authority [exousia] to trample on serpents and scorpions, and over all the power [dunamis] of the enemy, and nothing shall by any means hurt you. Nevertheless do not rejoice in this, that the spirits are subject [hupotasso] to you” (Lk 10:19,20)

“Having disarmed [apekduomai] principalities and powers, He made a public spectacle of them, triumphing over them in it.” (Col 2:15)

“Yet in all these things we are more than conquerors through Him who loved us.” (Rom 8:37)

“So He said to them, This kind can come out by nothing but prayer and fasting.” (Mk 9:29)

“But thanks be to God, who gives us the victory through our Lord Jesus Christ.” (1Cor 15:57)

“because you are strong, and the word of God abides in you, and you have overcome [nikao] the wicked one.” (1Jn 2:14)

“Therefore take up the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand.” (Eph 6:13)

“to open their eyes, in order to turn them from darkness to light, and from the power of Satan to God” (Acts 26:18)

“Heal the sick, cleanse the lepers, raise the dead, cast out demons. Freely you have received, freely give.” (Matt 10:8)

“No weapon formed against you shall prosper” (Isa 54:17)

“When the enemy comes in like a flood, the Spirit of the LORD will lift up a standard against him.” (Isa 59:19)

Reading: 2Sam 9-11; Lk 10