All you need to do is ensure that the Pokmon with the Big Parasol card attached is in your Active spot
This also works at instant speed, so you can use instants to protect your creatures from opposing removal
Rakdos colors also provide easy access to double strike, menace, and other helpful abilities that can help damage get through
But already, it seems, the spike has peaked, as today it's fallen back down to $52.50
If this causes the greatest power among creatures you control to change (for example, if you control a creature with "This creature's power is equal to the number of cards in your hand"), that new power will be used to determine the cost reduction
Building a sealed deck was reasonably simple, though I possibly had an advantage in having followed the card reveals and having a decent idea of what everything did