Owlbear Cub and Hua Tuo do not have summoning sickness.
An opponent controls at least eight lands and is unable to block and kill your creatures.
Steps
Activate Hua Tuo by tapping it, putting Medomai on top of your library from your graveyard.
Move to your combat phase, and declare Owlbear Cub as an attacker, attacking the opponent with eight or more lands.
Owlbear Cub triggers, causing you to look at the top eight cards of your library, put Medomai onto the battlefield tapped and attacking, and put the remaining cards on the bottom of your library.
Deal combat damage with Owlbear Cub and Medomai.
Medomai triggers, causing you to take an extra turn after this one.
Activate Altar of Dementia by sacrificing Medomai, causing target player to mill cards equal to Medomai's power.