Losing to someone who has 3 Raigeki spells in their deck while the player is only limited to one does not make the most sense.
As a player you have a small pool of cards, typically this is either 45 as with Draft or 84 cards in a Sealed prerelease, and its your task to create a deck out of that pool
The Archon is good in any situation, especially early on in a game where your opponents likely dont have many creatures in play yet
Take a look below at all the cards found in the Mythical Island pack, alongside their artwork and rarity
Notice how it just says "other card's effects", meaning it's not specific about what cards its unaffected by, just that it's unaffected by other card's effects in general
The box EV sits at roughly 8,617, which is above average for Pokemon TCG Enhanced Expansion Packs