Mana Confluence A rainbow land for a rainbow-themed Secret Lair, Mana Confluence might not be the best all-colours land out there, but it still sees plenty of play
for instance, a matchup I saw a few times was Thalia vs Scythe Tiger While Thalia could attack for 2 damage, and Scythe Tiger would die if it blocked her due to first strike, Thalia should not attack, because Scythe Tiger can then attack back facing no blockers
They would escape, causing the shift in the block's mechanics
Meaning that the regular Discard Filler will be probably one of the most common filler in existence (As it comes from 7 different sets since 2012)
Likewise, we already know about how the set will likely feature the quintessential D&D adventuring group thats the party mechanic in a nutshell
There are degrees, however