They are usually able to offer some sort of discount on cases and the amount may surprise you (as of this writing, paying around $470 USD for a case and the case incentive is not unusual, and the case incentive usually retails $50-$70 USD by itself, though they may drop as low as $30 after a few months if they are not popular)
While this guide covers common abilities, MTG has over 100 keywords including many expert keywords for specific sets
Dark Fusion is almost completely better than Polymerization except that Polymerization can be easily searched
Indestructible in battle, Apkallone negates the effects of any 1 card on the field the moment you Special Summon it, and when it finally goes to the Graveyard you can retrieve any Shaddoll card from your Deck or Graveyard, add it to your hand, and discard 1 card
Some of these monsters are definitely a waste of time to work with, while others flat-out make you win the duel
Storing your Pokmon cards in a safe or safety deposit box can provide extra security