Hes a chaotic court jester turned god of magic, with a penchant for destruction that leaves fire in his wake
Being able to quest with Merlin and then challenge larger threats with your supported character makes for a strong turn, especially when enabled by a common-rarity card
Karrthus is a decent example of a high-powered legend that immediately pressures life totals, but there are cheaper examples like Maarika, Brutal GladiatorMaarika, Brutal Gladiator, Kresh the BloodbraidedKresh the Bloodbraided (who starts small but can scale absurdly in the right deck), and Coram, the Undertaker (who is on paper a little fiddly but is easy enough in the format to make gigantic)
Timing rules still apply.) Mayhem represents an alternative cost that can be paid to cast a spell from your graveyard if you discarded the card with mayhem that turn
As long as its reliably a 3/3 or 4/3 with vigilance, I think its definitely worth playing
The soft fabric top and non-slip rubber backing provide a safe gameplay surface that stays in place