The stipulation of only creature spells hurts a bit, but this is definitely a sideboard card to bring in against creature heavy aggro decks, and not versus control decks
Roc of Kher Ridges Rarity: Uncommon TYPE: Creature SUBTYPE: Bird CMC: 4 Mana cost: USD: $13.66 EUR: 16.50 TIX: 0.00 EDHREC RANK: 30185 (3/3) Flying Rock Hydra Rarity: Rare TYPE: Creature SUBTYPE: Hydra CMC: 2 Mana cost: USD: $45.94 EUR: 21.18 TIX: 0.00 EDHREC RANK: 27176 This creature enters with X +1/+1 counters on it
Real quick, there is Jolly Gerbils as a one-off reward and incentive to give the most gifts
Play this if you expect and fear RDW and white weenie, play Goblin Guide if you expect and fear blue players
These kinds of effects that let you steal all of the abilities of cards from somewhere else can end up being very powerful, especially when they get to begin the game in your command zone
Rankle's Prankle also has the dreaded line of text "Choose one or more" so you can always customize it