The Temple's highest room has an altar. Once in ages immemorial, the altar showed an intricate detail on the creation of the Aztec universe. Now worn away, the table remains a powerful relic.This is still a tool of communing with the Teotl and request gifts. Once in their lifetime, a sacrifice must be made to the gods of the Teotl.
Sustaining the balance and continuity of the cosmos is what the Aztec gods do. While the Aesir would wait for Ragnarok or the Egyptian gods pray that the sun survives its nightly journey, Huitzilopochtli/Tonatiuh require amounts of blood and gore so that they can actually continue the world. Same goes for the rest of the gods (if one dies out, it can actually collapse the whole system that the Aztecs have fragilely rebuild).
A character who wishes to sacrifice must not heal their wounds after the sacrifice ends.
The very first sacrifice you can do is to understand the importance of such work. After sacrificing a small portion of your blood, you receive a boost in resilience for a century.
By sacrificing the blood of your enemy in the battlefield, you receive a boost in a battle. He can deal a large damage on an enemy in one strike or heal up to four wounds/injuries in the battle.
By sacrificing for the third time, one can perform some minor ritual sacrifices. The sacrificial victim must be willing to obey. All blood that has fallen are dedicated.
After five or more sacrifices, one can use an obsidian dagger to harm the user's enemies. Any blood that drops on the ground is ultimately given to the Earth goddess for nourishment.
By sacrificing a criminal, one gains a blessing of Tlazolteotl who will give a gift (whether it be a boost in stamina, health or dexterity) for the priest.
Intuned with the nature of sacrifice, children of the Teotl after more than fifteen sacrifices can offer the gods a part of their victim's bodies (either their heart, eyes, skin) or by certain events (either by drowning, decapitation or bludgeoning). Each god presided over such sacrifices will be satisfied and grant the user a larger and powerful boost (good weather, healing the band, warding off attacks from monsters or even cloaking the presence of the demigods from monsters) for up to three days, depending on how much you have sacrificed.