Actually, if you read the Grimoire cards (aka lore), what he said was true, for the most part. Nova Bomb: "Channel the Traveler's Light into a bolt of energy with the power of a collapsing star." Golden Gun: "...three rounds of sunfire" (I don't really know what that means" At least for the Nova Bomb, according to the lore, they are as powerful as a collapsing star. My theory on why it doesn't completely decimate the planet it's used on is because the Warlock purposefully holds back as to not destroy themselves in the process as the Grimoire also states "be careful in its use". Either that or the Warlock just barely taps into that power. If you read the Grimoire card for Warlocks, they almost seem way too OP as Warlocks have the potential to "shatter reality itself" or at least the secrets they hold do.