Liquid
Rootly supports the use of the Liquid templating engine in Workflows Tasks. Liquid provides a number of useful filters which can be used to manipulate the contents of options blocks. For example, the expression {{ 'hello' | upcase }} uses the upcase filter, when inserted into an options block it will render HELLO. You can string multiple Liquid filters together, with the expression processed left-to-right.
You can find our variables on the following pages:
Incident Variables
Action Item Variables
Alert Variables
Pulse Variables 
Expression: {{ "now" | date: "%Y-%m-%d" }}
Sample result: "2018-04-24"
Reference
Expression: {{ .my_array | size | times: 10 }}
Sample result: 50
Reference
Available filters