Spinback: win a bonus spin to Book of Tut every time you miss 5 rounds in a row. Collect 5 bonus spins to play. Spinback is only available on Sweet Bonanza and Scarab Queen.
Mega Symbols are game symbols that appear on the playing area and cover multiple symbol locations. Mega Symbols usually appear in 2x2 and 3x3 blocks and cover two or more reels.
There are other symbols that cover more than one row on a reel, Stacked Symbols and Expanding Symbols, but Mega Symbols differ from these in that they can cover two or more connecting reels.