Mr Irrgang takes the word 'borrow' literally in his third offering:
I've made a whole cycle of enchantment cards which help you, but then as soon as you're finished they turn around and help the opponent just as much or even more.
This is my favourite, as it also does something which no other card I've ever seen can do, and that's steal your opponent's cards straight out of their own library.
You can even steal their land so that later on you can cast their spells.
Generally, it will still be a big advantage to the caster because they get the first card. If it never leaves their hand, they can get around the penalty altogether. Of course you can't rely on what's going to be in your opponent's deck.
Just don't forget to give the card back when you're finished.
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