Sylvan Shepherd will always generate a lifegain trigger, Herald of Hadar will always deal two damage, Spiked Pit Trap will always kill the target, etc
Your opponents can just kill Rubinia to get their creature back and, as a creature itself, it's more vulnerable than enchantment-based Mind Control effects
Yuta Takahashi, World Champion XXVII 2/1 Illustrated by Joshua Raphael Standard Not Legal Alchemy Not Legal Pioneer Legal Historic Legal Modern Legal Brawl Legal Legacy Legal Comp
Play Boosters are the formats all-purpose option useful for Limited play, casual pack opening, or just building out a collection
Not to mention, you have to get several permanents out in play that are only one color, meaning if you want to make the most of it youd need five monocolored permanents out at once
I use TCGplayer and Amazon for most of my card-playing needs, but feel free to shop around a bit and try other stores