Ritual monsters are blue, and also cannot be summoned unless they are first Ritual Summoned
Boasting an expensive but nonetheless powerful tutor effect, Invasion of Ikoria works wonders in Commander
Commune with Beavers shows how green does this at common nearly every set and sometimes the extra cards go to the graveyard instead of back into the library
C Common Dark Contract with Errors X TRAP Continuous Once per turn, if you control a "D/D" monster: You can negate all Trap Card effects on the field (other than this card's) for the rest of this turn (even if this card leaves the field)
Run lots of cards that let you sacrifice and reclaim lands from the graveyard, and any kind of benefits from playing lands (Landfall), and you can demolish players life totals with Hearthhulls second power: sacrificing a land makes each opponent lose two life
Imagine being a Japanese kid and opening a pack of cards for the first time in your life and getting 10 whole cards