In The Elemental Evil Campaign, there are a total of 4 boons available.

 

Secrets of the Crushing Wave: requires 5 Fanatical Writings. You can choose between:

Wave of Force: +300 Power and +2000 Maximum Hit Points

Unassailable Tide: +300 Defense and +2000 Maximum Hit Points

Secrets of the Black Earth: requires 5 Promises of Power. You can choose between:

Heart of Stone: +4% Life Steal Severity Power and +2000 Maximum Hit Points

Earth's Renewal: +400 Regeneration and +2000 Maximum Hit Points

Secrets of the Eternal Flame: requires 5 Corrupted Texts. You can choose between:

Searing Aggression: +400 Critical Strike and +2000 Maximum Hit Points

Blazing Resilience: +400 Recovery and +2000 Maximum Hit Points

Secrets of the Howling Hatred: requires 5 Twisted Scriptures. You can choose between:

Bolstering Storm: Chance to gain bonus 10% Stamina Gain for 10 seconds when killing a target.

Furious Whirlwind: Chance to gain 10% bonus Lifesteal Severity for 10 seconds when killing a target.

Wall of Wind: When taking damage you have a chance to heal up to 24000 Hit Points over a few seconds. After this effect ends, your Recovery is increased by 1000 for 10 seconds.

Gale of Retribution: When taking damage you have a chance to heal up to 24000 Hit Points over a few seconds. After this effect ends, your Critical Strike is increased by 1000 for 10 seconds.

These boons are a part of the new campaign revamp (or shall I say separate). I would 'assume' the alternative campaign Cryptic decided to go with to replace the grind to 70 as it stands now. Thus, if a player has finished ALL campaign locations listed , prior to update (coming soon..?.?) he/she will get the boons. However, if he/she skipped an area or its a new toon, they will have to go back and complete the area prior to the boon being made available. 

This is my understanding. The update is coming........ sometime.