The Ascension Summon is available for a limited time each month. The Ascension Summon is an item Summon that contains combos of various Ascension Materials.
Each Summon returns a combo consisting of either 3*/4* Ascension Material plus a Trainer Hero of the matching Element or Class Emblems/Tome of Golden Emblems/Tome of Ascension plus a Master Trainer Hero.
Ascension Summons are conducted using Ascension Crystals. You need 10 crystals for a single Ascension Summon and 90 crystals for a bulk 10 x Summons.