Mexican flag is full of national symbolism. The green strip represents the Independence Movement. The white stripe represents the purity of the Catholic faith. The red stripe represents the Spaniards that joined in the quest for Independence and the blood of the national heroes. The emblem-shield symbolizes the Aztec heritage.
Throughout skyrim you will go to the Riften fishery and see a woman (Argonian) - No hair. She will say she might lose her job due to a Skooma addiction and needs a Cure Desease potion, once she had this a Goal will come up saying Find out the source of the Skooma.
How to obtain the power, Summon Karstaag, and it's related quest in The Elder Scrolls V: Dragonborn DLC for Skyrim. The power grants the ability to summon a powerful Frost Giant named Karstaag to fight for you for 120 seconds. NOTE: He can only be summoned THREE times. After that, the ability will no longer be available. To obtain the power, you must locate Karstaag's Skull in Glacial Cave and place it on his throne in Castle Karstaag Ruins. This summons the beast which you must then fight. Once he has been defeated, the power is received.