Your constitution score increases by 2, and your Strength increase by 1.

Blind trogs reach maturity at 15 years and can leave as much as 200 years sometimes even reaching 250 years 

Tieflings are about the same size of other humanoid creatures. your size can be medium or small 
your morphology is akin of a curved frog whit a bipede posture 

Your base walking speed is 30 feet.
you also have 10ft of burrowing speed on lose ground like dirt and sand

You are permanently over the Blind condition but you dont suffer any penality on attack rolls and spellcasting on a 60ft range.

You have 30ft of blindsigth.and 10ft of tremor sence

You have advantage on steath checks when on caverns and stony terrain that matches your colour patern 
you cant use this feature when wearing medium and heavy armor.

you can cast Meld into Stone and Stone shape once per long rest if you do so you dont need verbal somatic or material componets. 

for several milenium your specie have lived underground your skin is addapted to that rough terain and the natural hazzards that it imposes dweling in the caves gives you the following benefits 

all damage you receive from piercing slashing and bludgening is reduced by 1+ half your proficiency bonus.  

you can give yourself advantage on constitution saving throws a number of times equal to your proficiency bonus per long rest.

You can speak, read, and write Common and Primordial