Both these artifacts cost four mana and let you pay an additional four mana to take a card from your hand and put it into play
It can hold up to a thousand cards if utilized properly, but just as Jeff Goldblum warns in Jurassic Park: just because you can do something, it doesnt mean you should do it
Im sure some players will get fancy and play with this effect as the general rule, just for fun
Of the two decks, I do think the Sapphire and Steel deck is more straightforward
Players may Pendulum Summon once per turn, Special Summoning any monsters from their hand, and face-up Pendulum Monsters from their Extra Deck, whose Levels lie between the two Pendulum Scale values (exclusive)
Trainer Cards: Provide special effects, like healing or drawing extra cards