they're very weak because back in the day, the designers thought that being a 'legend' was enough to give them an extra advantage
With Estheim in your command zone, you now want to be gaining as much life as possible and Beacon of Immortality goes from an interesting curiosity to potentially one of the most valuable win conditions in your deck
It's also not too hard to reduce artifact mana costs
The new characters are part of an effort to reflect Dungeons & Dragons [as the] game is now, not as it was 25 years ago, Wyatt added
Unlike many higher hitting stuff you don't have to hold out mana or keep something untapped like a dork or a land, you can just do your thing and then keep the Chains ready
Elspeths Nightmare Elspeth's Nightmare is good early game removal since it can also help you avoid a threat in a players hand, and then exile it the following turn