Both standard and special sets have ETBs, and if you're lucky, you can also try to grab the Pokmon Center versions
Some of the best include Valakut Exploration , Chandra, Torch of Defiance , Light Up the Stage , and Commune with Lava
There are eighteen in total: Decidueye ex (super rare) Dhelmise ex (super rare) Incineroar ex (super rare) Crabominable ex (super rare) Wishiwashi ex (super rare) Alolan Raichu ex (super rare) Lunala ex (super rare) Passimian ex (super rare) Alolan Muk ex (super rare) Solgaleo ex (super rare) Acerola (super rare) Ilima (super rare) Kiawe (super rare) Guzma (super rare) Lana (super rare) Sophocles (super rare) Mallow (super rare) Lillie (super rare) These are all the special art rare cards (two stars) in Celestial Guardians
While you need to have a strong theme for a good deck, always make sure to have some staple cards too
(1): This is my favorite boss monster to summon
You should rarely use removal before the Heliod player initiates their combo, because all the abilities involved on their side work at instant speed they could simply go off and win the game right there, all with your Lightning Bolt stranded there on the bottom of the stack