During each sets Game Day, you could play against a special Challenger Deck, using your hero cards as support
When the last is removed, cast it without paying its mana cost
We ended up doing life gain with card draw (akin to a cantrip)
Likely because SV 151 also introduced a Special Illustration Rare (SAR) version of Erikas Invitation with even more elaborate artwork, which stole the spotlight (and a higher price tag)
The lifegain mode is minuscule in Commander, and the option to counter a loyalty ability won't present itself all that often, which means the default modes are making some Squirrel buddies and exiling a player's graveyard
Theyre essentially the same card, but Waves of Aggression is multicolored, although it can be cast with hybrid mana