To complete the Quest, you will need the shield, the Pegasus Strike, and all 4 Gauntlets, with all except Gaia being upgraded.
To light the Eternal Flame and begin the Easter Egg, you will need to complete the Oracle's challenges.
On 1-Player, claim 2 epic rewards
On 2-Player, claim 3 epic rewards
On 3-Player, claim 4 epic rewards
On 4-player, claim 5 epic rewards
You'll know that you are successful when the Flame turns blue.