I plugged in a couple search queries: "delve," "convoke," "cost less to cast," "rather than pay this spell's mana cost," things like that to see what I could find
Dragons of Tarkir gave us five newcomers (Dragonlord Silumgar, Dragonlord Atarka, etc.), Core Set 2019 gave us retrains of the originals (Arcades, the Strategist, Nicol Bolas, the Ravager), Strixhaven added five more as the namesakes of the different schools (Tanazir Quandrix, Beledros Witherbloom, etc.), and the five metal dragons from Baldur's Gate were also given the double creature type (Ancient Bronze Dragon, Ancient Copper Dragon, etc.)
That said, the best clue commanders have some sort of payoff for creating or sacrificing Clues beyond just letting you draw extra cards, whereas legends that just make Clues for the sake of card advantage will rank a little bit lower
I understand that, but then I see all of these life-gaining cards played as well, such as creatures with life-gain when they enter the battlefield (ETB) or other spells
It also makes up for a very explosive combination that lends itself to more aggressive strategies, whose sole aim is for the opponent to lose life
