Rule 313.2 · Vanguards
Vanguard cards remain in the command zone throughout the game. They’re not permanents. They can’t be cast. If a vanguard card would leave the command zone, it remains in the command zone.
Ask the judge Pro
The life counter has an AI judge that answers your play citing the exact rules. It is part of Gatewatch Pro; the rules, Oracle text and rulings stay free.