what happens if 2 dolls target each other? does the effect just target each doll once?
also, the purpose of a 'real life voodoo doll' is to inflict pain on somebody, so it doesn't seem quite right for it to allow buffing of a creature. I feel that it would fit the name much better if it had either the ability to deal X damage to the linked creature (or maybe player?) whenever it is targeted by a spell or ability, or something like that. Or, maybe just an ability that deals a certain amount of damage to a linked creature, maybe dealing 1 damage per turn to the 'first' enemy creature (first meaning closest to the original spawn point, so if there is nothing in the first creature location, it moves on to the second or third)
Also, what happens if the doll is gravity pulled? does it gravity pull both creatures, then make your doll defend you while killing the enemy creature? That would be kinda cool.