Level at least 1 of them at 3/70 and play with them at the medium or difficult map stages. Whoever the hero you find useful, ascend that one.
Elena is decent both in offense and defense due to her riposte and high attack stat, especially if you get her costume since it adds to her stats and reduces mana requirement. Her bane is basically her low defense. Emblem may somewhat remedy that issue.
Noor is one of the summoner fire legendaries, along with Red Hood, Santa Clause and Puss in Boots. She is slow though but may be relevant in the current minion summoning meta. She is one with a buff request thread in the forum.
Reuben is a late hero in that he would have been one of the best counter for the GTV trio pre-nerf. Now that Velluria aint much as oppressive defensively like they were once before, Reuben’s release as a HOTM as a much needed hero is DEAD. But he hits 3 and is the only fast hero among your choices. You may find him and Noor benefiting with each other’s minions.