07.01.2017 14:47
You can get Immortep, for surely, and some more legendary heroes from 7-day rewards. Plus, each 30-day of the game calendar will give a special hero card reward that contains some legendary heroes. Of course, you should enter game every day if you want to acquire this card.
Also, you can get heroes from legendary hero cards that can be purchased for 13000 merits in the Warehouse. Besides, this card can be obtained as Mesa Boss reward or through some events.
If you want to get legendary heroes through gem rolling, you should know that developers make a random system that gives you legendary heroes accidentally. Tricks or hints don't work because all depends on random results.