There were only twenty Lesson cards, so to up the as-fan, the designers made two things: five colorless Lessons and five hybrid Lessons
A common interaction is to attack for 4 in the hope that your opponent will try to kill it, and you counter their removal to then hit for 6
From the control classic Counterspell to the painbow banger, Jodah, the Unifier, almost every card in the Spongebob Secret Lair offers just as much substance as they do style
It steals cards from the top of each players library, allowing you to play them yourself using any colors of mana
The only reason I have personally never bought into is that in my gaming group, at the time, we had a lot of stuff going on gaming wise and it was a rare situation where economically I had to make some tough calls
Mirkwood Bats even works well for decks that aren't necessarily sacrificing all their creatures