I don’t have Hel but I have Proteus. If any of their skill is activated, then Onatel’s skill is useless as she cant accumulate mana from enemy heroes not charging mana due to the mana freeze. Even if there are 5 enemy heroes in an opponent team, you cannot truly rely on A.I. to do the intelligent thing. Hence, don’t mix in a defensive team Onatel with Hel, Proteus, Guinevere, etc, or you wont get to maximize and optimize all your heroes.
One more thing, if your Aegir is emblemed to +7 (defense and health nodes up), I rather have him flanked with your maxed and emblemed Azlar. Come to think of the number of times Azlar would fire his skills. Your opponent needs a green stack and with unfavorable boards, they may need Melendor or Caedmon to dispel immediately Aegir’s skills. Unfortunately, there is no green cleanser for Azlar’s DOT.
EDIT: I think Azlar can fire twice and its game over. Volcanic Eruption activated thrice is too much. Makes me think to level my second Azlar to both flank my Aegir (I see no better blue hero to serve as tank) but i lacked the scopes for his final ascension and I am prioritizing Lepus yet as my blue team specializes on damage 3 heroes (Frida+Grimm+Athena+Ariel+3/70Richard), aside from the fact that Paladin emblems are given to my Ares.