Any spell can trigger this blue enchantment (unlike Esper Sentinel or Mystic Remora, for which you need a noncreature spell), and it has no downsides or per-turn limitations
It more or less doubles your mana investment, while also allowing you to create a lot of bodies to block or attack with
Youll avoid any feel bads, and you can construct your deck to deal with the creatures anyways, while your opponent burns
Or worse, youre diving into the underworld prison of Tartarus
Costing two generic and two black mana for a 4/3 snake glimmer enchantment creature, Enduring Tenacity has some board presence, but for the most part it's considered purely for its triggered ability: whenever you gain life, target opponent loses that much life
Even magic rings were not much use against wolvesespecially against the evil packs that lived near Goblin-infested mountains