In Path of Exile Maps from buzai232's blog

In buy poe currency Maps provide the endgame content. Their quality can vary just like items and they can be magic, rare or unique. They also have their own special affixes and these increase the difficulty of maps as well as their rewards. Maps also have quality which can be increased by Cartographer's Chisel. Maps can be opened in the Eternal Laboratory which can be located in Act3. Eternal Laboratory cannot be used as long as you did not complete Lady Dialla's quests in Merciless difficulty.

You can also have your own Map Device in your hideout, this can be obtained from Zana. After you have opened a map you will have six portals. Each portal symbolizes one try. If there are no more portals left you cannot finish the map so pay attention for this. You can use Portal Scrolls inside a map but if you go back down one Portal will close. Maps can be found from anything that drops items that is at least level 60 or higher. There are several map tiers and each tiers are dropped in different places. Non-map areas can only drop tier one maps. Higher tier maps can only be found inside other, lower tier maps.

Every monster has a chance to drop maps one level higher than the map they are in. Bosses can drop a map that is higher by two levels than the current one. Maps are split into three tiers. Different tiers unlock new and more difficult map mod combinations. Vendors can also exchange 3 maps of the same quality to a one level higher map.With Vaal Orb your map will become Corrupted and cannot be modified further. In this case bosses from corrupted maps have a chance to drop Vaal Fragments or Vaal Skill Gems.www.buypoecurrency.com/