This issue is a variant of Adventure Comics (DC, 2009 series) #7 / 510 [Regular Direct Cover].
Indicia reads: Adventure Comics #7/Adventure Comics #510 (Variant Cover).
Incentive cover shipped in 1:10 ratio to standard cover. Cover is an homage to the cover of Adventure Comics (DC, 1938 series) #300.
"Special thanks to Geoff Johns, Eddie Berganza & Adam Schlagman."
from First Wave (DC, 2010 series) #1 [Standard Cover] (May 2010) [preview of cover and 4 story pages]