373 cards found matching energy cost is at least 4

Adaptatron
Ahri, Alluring
Akali, Silent
Akshan, Mischievous
Albus Ferros
Alpha Wildclaw
Ambessa, Respected and Feared
Ambessa, The Wolf
Ancient Warmonger
Angler Beast
Anivia, Primal
Annie, Fiery
Annie, Stubborn
Aphelios, Exalted
Applied Researchers
Arachnoid Horror
Arena Kingpin
Arise!
Armed Assailant
Ashe, Focused
Assembly Rig
Astral Heron
Atakhan
Aurok General