I provide details on Miracle ticket mechanics at several points throughout my guide.
I'd save for Thanatos and see if you can pull her. Might want to hold your Miracle ticket til then also.
Soul priority will depend on first Miracle ticket pick, but Gawain > Joan > Cassiopeia > Mordred would be a general priority order.
Hint: Replace "Miracle ticket" with "tax" to uncover the hidden meaning.Always consult with a professional Miracle ticket advisor before acting on advice you see on the web.