The MTG Lord of the Rings: Tales of Middle-earth crossover is arguably one of the most ambitious projects the TCG has ever embarked on
If you really want to commit to the Sirens Call and Angels Trumpet idea, you can springboard off the Mandate of Peace idea and just play Peacekeeper and other cards that prevent creatures from attacking
However, two commanders that caught my eye might bear consideration: Ertai, the CorruptedErtai, the Corrupted needs a creature or an enchantment to sacrifice in order to counter a spell
(Scryfall note) If you win the clash, you destroy all enchantments all of your opponents control, not just enchantments controlled by the opponent you clashed with
It actually felt like it had depth and power in the way a goblin deck does
The Haunt of Hightower The Haunt of Hightower is a mill/discard synergy creature