Once you cast the spell, activate the ability, or put the triggered ability on the stack, the crime has been committed
With copies of [c]Thoughtseize[/c], [c]Inquisition of Kozilek[/c], [c]Wrench Mind[/c], and more, it reduces the opponents hand to zero cards so that they cant play any threats
You must be able to use your mana efficiently on every turn
Of course there are better cards to drop second lands, like Oracle of Mul Daya
8 Primeval Spawn Primeval Spawn's design feels maybe a tad too forced and uninspired, given its initial printing in the 'Painbow' precon, a deck focused on 5-color spells
In 1v1 this will just probably win the game, but at 12 mana or requiring Madness shenanigans, it should