EDIT: I believe they have changed it to that when the Mirage Blueprint finishes is when the next riddle will be issued.
Mirage is the first Warframe to fully take advantage of the new questing systems.
You can find her quest by going to the market place and buying the Blueprint Hidden Messages. The Quest Blueprint costs 5,000 Credits, 5 Orokin Ciphers (From Orokin Derelict runs), 4 Oxium and 1 Argon Crystal. The Quest Blueprint requires a 6 hour build time if you don’t use platinum.
After the Quest Blueprint has been finished, you will receive a message in your inbox containing a riddle.
Three parts, three acts, three riddles for thee
to revive the one wielding fantasy
Ancient gods so cruel, once ruled from on high
Can you name their peak where the land meets the sky?
The Riddle points you towards Mars, Olympus. Upon completion of the mission, you will be rewarded with a Mirage’s Helm Blueprint. This mission has the same tileset as the Breeding Grounds and the music has been changed into something really creepy… I’m serious.
To build the one you think witty,
seek the nymph who sang oh so pretty.
She lured him in with her song and a grin,
his wife must’ve thoguht it a pity.
When you start building you Mirage Helmet Blueprint you will be once again be message with another Riddle. This time it will point you towards Saturn, Calypso where you can obtain Mirage’s System Blueprint.
Three acts complete, the end draws near,
soon Mirage will cause enemy fear.
Memory lost, to be reborn,
a new warrior rises, duty sworn.
The cycle continues and the last riddle will point you towards Charybdis, Sedna to obtain the last part of the Mirage’s components, Mirage’s Chassis Blueprint. After accumulated all of Mirage’s required components you can now build Mirage’s Warframe.