Easiest way:
Proccesion1, Procession2, Procession3, Fortress1, Fortress2
Play Lab, draw
Play Procession1, Play Procession2 twice, Play Procession3 twice:
--With procession3 -
Play Fortress1 twice, get +2 actions, draw Watchtower and Diadem.
Trash Fortress1, gain BoM on top of your deck, fortress back into your hand.
Play Fortress1 twice , draw Bom + Whatever.
Trash Fortress, gain Bom on top of your deck. fortress back into your hand.
With procession2
Play Fortress1 twice, get +2 actions, Bom + Whatever.
Trash Fortress1 gain Market on top of your deck, fortress back into your hand.
Play Fortress1 twice , draw Market + Whatever.
Trash Fortress, gain Market on top of your deck. fortress back into your hand.
Now you have 1 processions in play, 2 BoMs and 2 markets and 2 Fortresses in hand.. Just repeat this indefinetely, with BoMs posing as Procession until you get 10.000.000.000 spare actions and same amount of spare Markets, than play Markets out.
Than play Diadem.