2 5 8 x 3 5 8 card sleeves BCW Sleeves, 5/8 5/8" Often referred to as penny sleeves Ultra Pro - Ultra Pro:

Here, seven different legendary creatures each had a serialized treatment, albeit with print runs now cut again so as to reduce the final total to 1,750 total serialized cards (each legendary creature having a run of 250)

It has the added bonus of (most likely) not killing your Leviathan if you need to cast one after the Big Kahuna is online

A Flash counter and or blocker, there's some very fun way to use this, especially during things where your opponent may assume they're safe to be greedy, such as on a turn-ending before untapping fully, and I agree with Loxi: players like to tap out a lot carelessly

It can lead to some interesting plays, however, trading out Fire Fists