Someone can easily stop you from casting spells for a bit if they can stop your method of sacrificing this reliably, so you really have to make sure you can always pitch this thing if you don't want to lose half of your starting life
If in your investigation you determine that the player intentionally broke the rules, then the penalty should be cheating, followed by disqualification
To be honest, youre going to be playing against the starter deck a LOT before dealing with the bigger stuff, so you dont even have to have a completed amazing tier 1 deck to start
That comes with a cost, as TCT decks often look quite similar because they have a relatively small pool of cards to draw upon
It has it all
Elvish Piper is superior because you can cheat your creatures out at instant speed and not just during your attack phase, plus it doesn't become exerted, but at least the champ saves you the mana cost to activate