I finnally managed to make it, when the brew master splits into elementals each of them gets 1/3 of the Brewmaster's inventory, when they die / the timer expires their inventory is merged into the brewmaster's, the elementals can use their items and get passive bonuses.
In maps where you want to use Sef related spells but you want to balance it a little with other ultimates ( Metamorphosis > Normal Storm, Earth and fire ) Since the panda loses his items his ultimate makes him weaker instead of stronger