the same deep water as you

1 1/2 oz Plantation Dark Rum
1/2 oz Del Maguey Mezcal Vida
3/4 oz Tamarind-Cinnamon Syrup (*)
3/4 oz Lime Juice
1 dash Angostura Bitters

Shake with ice, strain into a Collins glass, fill with crushed ice, add a straw, and garnish with a mint sprig (later, it was a mint sprig + a paper umbrella).
(*) In a pinch, substitute 3/4 oz cinnamon syrup and 1 tsp tamarind concentrate such as Tamicon from an Indian spice store, otherwise follow the directions below.
(*) To make this syrup, break up 4 cinnamon sticks and add to 10 oz water in a pot. Bring to a boil and simmer covered 10 minutes. Add 10 oz sugar and 4 oz tamarind concentrate, stir while bringing back to a boil, cover, turn off heat, and let steep for 2 hours or more before straining.
In thinking about other ingredients to bring to the Cocktail Lab at Earl's Prudential two Mondays ago, I thought about tamarind syrup and recalled how well it paired with rum, cinnamon, and lime in the Final Countdown. Veering from that drink's Jet Pilot format, I dropped the grapefruit juice to make it more of a Test Pilot in structure and brought in a smoky mezcal akin to the Mr. Howell Daiquiri utilizing Scotch. I took the drink in a Tiki direction by serving it over pellet ice with a mint sprig (and later a paper umbrella) as garnish, and I kept with The Cure's Disintegration theme by dubbing this one The Same Deep Water as You.