Once a creature that has reach because of Sphere Grid's last ability has blocked a creature, removing all +1/+1 counters from that creature or causing Sphere Grid to leave the battlefield won't cause that creature to stop blocking
High Perfect Morcant makes your opponents blight their creatures when elves enter the battlefield, while using those same elves to proliferate
Neheb, the Worthy Rakdos has the colors you want to play with minotaurs
These cards will only be legal in the formats in which they are already legal, but Limited is a different story
Gonti, Lord of Luxry I wanted to rate this higher but it seemed highly unreasonable putting above any of the latter cards in this list
Its also really easy to break, as all you need is two creatures that can flicker each other, which not only produces infinite +1/+1 counters on your creatures, but also scales firebending up to make infinite mana when Zuko attacks