pokemon jumbo cards list XL Oversized Toploaders Jumbo cards (TCG) - Bulbapedia,

Sure, the fact that the Shambler has kicker means it doesnt work well with some Slime tricks, such as flickering or recursion for triggering its ability, but its a 3/3 beater that can destroy a planeswalker

We are keeping the description general here since the printed treatment rewards being seen directly rather than recalled from a summary

Instant March of Reckless Joy As an additional cost to cast this spell, you may exile any number of red cards from your hand

You will be able to find these ichor cards in Set, Draft, and Collector Boosters as well as select cards in the Collector Booster Sample Packs that come with Commander decks

Thus, you cant really slot it into every single deck as freely as of the Evoke Elementals

It is believed that the concept behind this mechanic is taken from a Japanese philosophy featuring five elements, the fifth being the Void