Healing a vampire

Hi!

Let the first army be [Vampire, Healer], and the second be [Warrior]. Be the vampire alone, after the first strike his health will be 42 (40 + 4 * 50%), as there is no limit on his health (at least, neither in the task description, nor in the tests). If he is supported by a healer, that healer heals him, diminishing his health back to 40, as

health after healing can't be greater than the maximum health of the unit

Am I right? Does the healer heal before or after the attack of the first unit? Can the healers reduce the ally's health? Or the vampire's health couldn't be greater than the maximum health in any case?