I'm running Princes of the Apocalypse for my group, and they're about to encounter their first elemental prince, Yan-C-Bin (p. 220). I see that he has the following ability:
Summon Elementals (1/Day). Yan-C-Bin summons up to three air elementals and loses 30 hit points for each elemental he summons. Summoned elementals have maximum hit points, appear within 100 feet of Yan-C-Bin, and disappear if Yan-C-Bin is reduced to 0 hit points.
The part I'm confused about is "maximum hit points." Air elementals have their hit points listed as "90 (12d10+24)" in their stat block.
Is this line meant to make sure people are deploying a fully-healed air elemental as opposed to one with 30 HP (regardless of whether they use the average hit points or they actually roll their hit dice), or is it meant to convey that these are extremely robust air elementals and each should have the maximum possible hit points as decided by the hit dice, 144 (120+24), and the fully-healed part is implied?