white magic

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Magic or incantation practiced for good purposes or as a counter to evil.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun idiomatic Magic derived from good or benign forces, as distinct from evil or malevolent forces; or magic performed with the intention of doing good or giving aid.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun magic used only for good purposes