New King James Version
and to have power to heal sicknesses and to cast out demons:

King James Bible
And to have power to heal sicknesses, and to cast out devils:

American Standard Version
and to have authority to cast out demons:

Berean Study Bible
and to have authority to drive out demons.

Douay-Rheims Bible
And he gave them power to heal sicknesses, and to cast out devils.

English Revised Version
and to have authority to cast out devils:

World English Bible
and to have authority to heal sicknesses and to cast out demons:

Young's Literal Translation
and to have power to heal the sicknesses, and to cast out the demons.

Mark 3:15 Additional Translations ...