rolldice:tldr:17d0e

The command "rolldice ${2}xd${20}" is specifying a roll of two 20-sided dice, using a variable substitution.

Here's a breakdown of the command:

1. "rolldice": This is likely a command or function that performs a dice roll.
2. "${2}": This is a variable substitution. The value of 2 will be substituted in place of "${2}" in this case. It indicates the number of dice to be rolled.
3. "xd": This is a notation commonly used to indicate the number of dice to be rolled. In this case, it means "x" number of dice, where "x" is the value of the variable substitution (${2} in this case).
4. "${20}": Similarly, this is a variable substitution. The value of 20 will be substituted in place of "${20}". It indicates the number of sides on each dice.

So, when the command is executed, it will essentially perform a roll of two 20-sided dice.