If you’re unfamiliar with Treasure Trooper, I discuss it in much more detail in my blog article.
The Dragon Portal can be purchased for 25 dragon scales at Cogg’s Coop.
Although this is a significant outlay, it allows your dragons to go on daily “quests” where you can find prizes such as gold coins and boosts for fights (tranquilizer darts etc). If you intend to invest in your dragons and enter fights this can be useful.
However, it is possible to get unlucky and end up with your dragon in the sick bay (requiring medicine costing 5 scales) so I tend to be quite cautious about sending my dragon in nowadays. I got the below quest twice in a row once – that was frustrating.
You sometimes find monsters to fight when you enter the portal which rewards you in cash if you win.
Note that you can only send one dragon on a quest each day.
Spare Time Income 