All of these cards can be cast for their front side casting cost, or the alternate More Than Meets The Eye cost, to have it enter the battlefield converted on its back side, similar to transforming effects found on many werewolf cards
Red So we have Knowledge Pool, and we have Thousand-Year Storm, and well, Im sure they had a great time together, because now we have Arcane Bombardment
Instead of being the one who gets surprised when your opponent casts an instant and boosts their prowess creature, cast your combat tricks to buff your own creatures
Attached to an evasive creature like Invisible Stalker, this card ensures your life total never gets close to 0
They really get back to the basics, and for kids in particular I think they are an effective way to focus not on what Trample does, what Fly does, and so forth but on the REAL way to play the game
Conclusion Each of the Game Changers are powerful in their own right