If you use Enhance runes on HP tanks, look for speed, % HP, %Crit damage and primary stats as substats in all runes.
Since Enhance rune set effect works on all allies, you should focus on your main purpose as a team: having a good amount of HP is a great feature to have in context such as Farming, ToA, Cairos Dungeons, Arena Defense, Guild Battle Defense, Live Arena and Raid Battle. Enhance rune set effect works good if you have HP based damage dealers, HP tanks, revivers or support on your team, such as:
You can equip this rune set on every whatever monster you may like, even if it’s not a HP tank, since the effect will be added to all the monsters on your team.