Spelling Bonus: Spelling F-U-E-L qualifies the Fuel target for temporary double scoring, and spelling M-E-T-A-L-L-I-C-A starts "And Justice for All..." for cumulative increasing scores.
Many potentially powerful creatures are ruined by drawbacks like echo (pay their casting cost again on the turn after you play them or sacrifice them), cumulative upkeep (pay an increasing cost every turn or sacrifice them), and many, many more.
With Metallica, spelling F-U-E-L qualifies the Fuel target for temporary double scoring, and spelling M-E-T-A-L-L-I-C-A starts "And Justice for All..." for cumulative increasing scores.