The Spindrift Isles can be attacked only by flyers or swimmers. It can defend itself as a level 8 elf wizard.
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TSR
Wizards of the Coast
This is a coastal realm. Due to its severe restriction on the number of champions who can attack it, this realm is an excellent choice for placement in the front rank. A realm can only be attacked by swimmers if The Mistmarsh (13/DR) holding is attached.
Gloriana (3/1st-chase) and Aquilla (98/UD) defeat flyers and swimmers respectively, so they are good champions to have in the deck for defending this realm. The realm also has the advantage of being able to defend itself if needed, as well as being an elven wizard.
Additionally, spells can now be used in addition to allies, as well as events that benefit elves, such as Drow Justice (21/UD). The Labyrinth of Castle Greyhawk (6/DU) would also be a good choice since this realm will likely be the target of spells, events, and psionic powers that will instantly destroy it.