Such a visible defect, which may be relevant for gameplay, requires careful assessment, considering both the cards preservation and the functional impact of the defect
The market rate for these cards changes over time
While that's an ideal scenario, even just playing this for one or 2 mana is excellent, and casting it for the full four isn't completely embarrassing
Basically, it leaves no hope for your opponent to do anything but concede
The enter and attack trigger on Krang & Shredder takes cards from opponents decks, and with a permanent leaving the battlefield under your control (easy), you get to play those cards for free on your end step
We will hamper their ability to wage war against us with the application of cards like Nature's Will and Sword of Feast and Famine