Umbra armor's effect is applied no matter why the enchanted creature would be destroyed: because it's been dealt lethal damage, or because it's being affected by an effect that says to "destroy" it (such as Nekrataal's triggered ability)
One thing to take note of, they even have a collection of vintage cards (those with the Pocket Monsters back) sold for 550 so come here if vintage cards are what youre looking for
Then when it ETBs, you can phase out any number of other dorks from the battlefield, also to answer the same stuff, but this will answer things the indestructible former one gives like mass bounce of Cyclonic Rift or Aetherize, or exiling of Farewell or -X/-X of Mutilate or sacrifices of Living Death
Tempest Technique Tempest Technique brings elegant synergy to enchantment-heavy decks, and of course, Voltron ones
Weakness: Grass (x2)
Lyzolda, the Blood Witch There are plenty of Rakdos sacrifice commanders we can pick