Those are the angels at 20+ mana and yes her mid-range creatures, which if you look are her average, are very successful with proper healing. The priestess plays well by surviving at first since her spellbook is more costly to play, but with proper amounts of aegis and healing and utilizing guard to be advantageous, she becomes the most threatening mage to play against. This is a mage that benefits from mana crystals or flowers to have the mana per turn to cast a cost 12-13 creature to protect her while she offers them the same protection.
Shadow is correct on the other mages play styles too, but on the warlock and wizard, curses are also very handy intentional casts to force opponents to either face the action and mana cost to dispel or face the consequences of direct damage or slow. The beastmaster is also a master enchanter for buffing those creatures to be unstoppable! Have fun!