Vivienne requires the heart of a wyvern to complete an alchemical formula. Though all wyvern hearts look more or less the same, she specified that it needs to be from a rare beast known as the snowy wyvern however she does not specify at this point why she needs the formula.
The "wyvern" in question is in fact a white Gurgut, located in the northern part of the Exalted Plains. The Inquisitor needs to unlock and complete the war table operation Gain Access to Ghilan'nain's Grove in order to access the grove where gurgut are located; the location for acquiring this operation can be found a ways east from an ocularum, north of Fort Revasan. It costs 5 Power to complete.
To find the snowy wyvern continue on north from the entrance to this area, following the quest marker. It is also possible to collect a heart from normal gurgut in the area and return it to Vivienne, pretending it's the heart she seeks. Keep in mind there is a dragon near the eastern edge of the same area if not already killed, so it is advisable to stay close to the western edge where the wyvern is located if not looking for a tough fight.
Upon returning to Skyhold, hand in the quest to Vivienne.
- 1,025 XP
- 400 Influence
- 3 Power
If either the common or snowy wyvern heart is given to Vivienne the quest completes immediately, just before the cutscene with Bastien. The following two items are not received until after a follow-up conversation with Vivenne at Skyhold:
- Hat of Majesty
+10% Spirit Resistance
- Enchanter's Seat (Mage throne)
- With the exception of the "no deal" option, rewards are always the same, regardless of the conversation choices.
- Whether the Inquisitor lies or gives Vivienne the real heart, Bastien's fate is always the same.
When returning to Vivienne with the heart, the Inquisitor is presented with a conversation choice. Results are as follows:
- I've got the heart. Now talk. - Vivienne Disapproves
- I've got it - Vivienne Greatly Approves when talking to her again
- [Lie.] I've brought the heart. - Vivienne
- Not yet. - Ends the conversation, quest remains in the Journal
If Inquisitor gives Vivienne the real heart, the next conversation the Inquisitor initiates with Vivienne relates to her history with her lover. If given the common wyvern heart, Vivienne will reveal that she's aware of the Inquisitor's duplicity. Further approval gains and losses can be seen here.
- There is a possible bug in which, after giving Vivienne the common heart WITHOUT facing or looting the Snowy Wyvern, rewards will be given as if the quest is complete, but it will remain incomplete within the journal. It is also possible that the Snowy Wyvern will not spawn in this scenario.
It is recommended to obtain both hearts and present the false one with both in your inventory if you wish to deceive Vivienne.