Bugs:
If the player tries to teleport to a full map, the player will be unable to do so but the item will still be used, effectively wasting the item.
Also, if try to teleport to a Heart of Thorns map without owning the expansion, the item will still be used and effectively waste the item.
After trying to Teleport to Friend about 10 times I realized I had way fewer of this consumable. Went to the wiki and see the bug report.