Strength of the fallen

Discard Clocktower Sentinel into void

Fetch some charge or overwhelm for Skeletal Dragon and Shield of the Line and make huge damage to opponent.

Earth Conjuring can buy you time

Twinned Spiteling is a good defence

Valles Rex can surprise opponent against Flying and cost can be low if they is huge card in the void.

Ephemeral Wisp you can let them stay a bit in your void to let Clocktower Sentinel beef them up and then it's good blockers each time you get power card.

Very fun to play, but don't expect to win most of your games.