And we honestly don't know what's toxic to Miqo'te, Elezen or any non-Hyur. We might not even know what's toxic to them, since physiology in a fantasy world can work differently, same with properties of metal being different. It kinda boils down to the author with the finer details.
But yeah, I think some of the largest limits will be in the number of spells as there is limited space on the body... the complexity of it and the mastery over the type of spell casting that the character has. I'm inclined towards limiting the spells to the character's own aether instead of providing an external source, because mana pools are finite and drawing from the sea of aether that all Hydaelyn exists in could lead to power playing.
But yeah, I think some of the largest limits will be in the number of spells as there is limited space on the body... the complexity of it and the mastery over the type of spell casting that the character has. I'm inclined towards limiting the spells to the character's own aether instead of providing an external source, because mana pools are finite and drawing from the sea of aether that all Hydaelyn exists in could lead to power playing.
