Imbue Maps

In act VI Anya will sell you items that allow you to imbue maps:
 * A Zakarum Orb can be combined with a White map, a Rune of Thul or higher, and a jewel to produce a Yellow map
 * An Angelic Orb can be combined with a Blue map, a Rune of Thul or higher, and a Perfect Skull to produce a Yellow map
 * An Horadrim Orb can be combined with a Yellow map, a Rune of Thul or higher, and a Perfect Gem to produce a rerolled Yellow map