No creature is immune to any kind of damage unless its stat block explicitly says it is.
Its sole weakness is radiant damage, so not only is your good cleric or paladin its juiciest victim, he or she is also the one who’s best equipped to defeat it. While it does create creatures, the spell is cast by targeting objects, therefore it cannot be twin spelled. the spell targets a corpse (object) but creates skeletons / zombies (creatures).
You might be interested: FAQ: how long would you survive in the zombie apocalypse quiz? Can you twin spell animate dead?Īnimate dead is a wizard spell as well.