Many more bones were there than necessary, as some were to form a barrier; Jay wanted to waste as much of the knight’s time as he could, and this was simply part of his strategy.
As the skeletons are all level four, they each require fourteen mana to summon. Jay only has eighty-seven mana, but having just summoned four skeletons, it left him with a measly thirty-one mana. After using the mass summoning skill, it left only three. A far stretch from the fourteen needed to raise.
“It will be worth it.” He thought, “besides, the skeletons can take turns fighting, and use their bone eater skill to stay alive… without an enemy flanking them, they will hold on.”