Maralen of the Mornsong and Colfenors Plans are two just such cards that I happened upon way back in early 2008, the sets at the time in Standard were: Tenth Edition, Coldsnap, Time Spiral, Planar Chaos, Futuresight, Lorwyn, and Morningtide very cool sets that collectively had a metric butt-load of awesome cards, like Tarmogoyf, Mutavault, and Vendilion Clique
His +1 is both raw card drawing now and a lot of value later
While there's always a primary color, there's not always a secondary or tertiary color
Making Squirrels on entry and attack is solid, and being in green lets her access the token doublers that Krenko missed out on
The idea seems okay since we dont have to commit mana to the effort, meaning that well have a full tank for casting other spells on the turn were crashing the Siege