Omniscience

Omniscience is the ability to know absolutely everything. In age of mythology it is an improvement researched in the temple in the Mythic Age. Researching it will give you line of sight from all units, yours, allied, or enemy. Although this power is great, it comes at a large cost, which is an amount of gold that varies on the number of enemy units there are. The more enemies, the higher the cost, so if desired, it may be wise to research this as soon as possible since enemies usually train more units as time goes on.

Strategy Recommendations
The omniscience tech is incredibly useful late in-game. On a Random Map scenario, usually the enemy has resource-gathering sites scattered across the map, far away from his home city, and of course a market usually to accompany his gold-gathering efforts. Because using scouts to manually search out the map for enemy buildings an units is a pain, omniscience is a valuable time-saver. Also, if the enemy is using trickery or misdirection to keep you from knowing that they're train a mass of soldiers that counter your units, adequate time, you can train a counter-force to his.