Activate Mirran Safehouse using Faceless Haven's second ability by paying ({S} magic symbol) ({S} magic symbol) ({S} magic symbol) , causing Mirran Safehouse to become a 4/3 creature with all creature types until end of turn.
Activate Mirran Safehouse using Griffin Canyon's second ability by tapping it, untapping Mirran Safehouse and giving it +1/+1 until end of turn.
Repeat step 2.
Results
Infinitely large Mirran Safehouse until end of turn.