This Destiny: The Taken King guide provides details on how to unlock the Tlaloc exotic weapon. Before moving ahead it would like to share my personal experience of using this exotic weapon, it's one of the best and i am loving it. Now, without much ado here's how you can unlock TLALOC weapon in Destiny: The Taken King.
Step 1:
You have to reach Level 3 with the Gunsmith to receive the quest to unlock TLALOC. Please note this quest is only available to Warlocks.
Step 2:
You must get 100 Kill with Scout Rifles while having a primary or Scout RIfle telemetry active.
Step 3:
Receive 10 Weapon parts from dismantling rare or legendary Scout Rifles. I dismantle 2 year-one scout rifles.
Step 4:
That's it. You can now enjoy your new Scout Rifle.
If you need any help let us know in the comment section below.