The concept of the deck is simple - throw minions out on curve (tempo turn) and be aggresive, with semi-control of the board, while buffing the minions with health cards (Stormpike Aid Station & Power Infusion).
Mulligan for 1 (Keep Cleric, if you start with that & Psychic Courier),2,3, curve cost cards.
After obtaining board control with giant health minions, enter shadowform for extra dmg to enemy minions/hero - while having holy nova (with/without Bloodmage Thalnos) for minion heals/board clearence. Thalnos is a great edition due to low cost body, draw card, spell power for Deliverance, Holy Smite & Holy Nova. Don't be appealed to use your Power Infusions on Lightspawn immediately unless you can calculate a next turn lethal through other card means. Try to safe the Power Infusions till the enemy uses a spell/minion to kill your biggest board threat, otherwise use the Power Infusions on the weakest of your minions for enemy pressure, while maintaining decent remaining minions. Play Drek'Thar at all cost if you have a Stormpike Aid Station activated and it's safe for board clearence (in case it's late game). If you feel 2x Shadow Word Death is questionable in the deck and it's taking space - it's changable (would recommend swapping 1x SW: Death out with an Ironbeak Owl for an extra body and taunt/issue silence). Make sure to use Thrive In The Shadows for a proper situational use - don't use it blindly, unless you're comfortable with it. Brightwing & Psychic Courier are good for low cost bodies that gives extra cards which can benefit a lot.
Former High Legend player from years ago (casual now)
Proof of player & former high legend, playing against a former pro player and that the deck belongs to specific player in the picture containing link below: