Merge Dragons Guide & Tips

This one is kind of sketchy, given what the terms state. The terms state to complete Foothills 4, but there is no Foothills 4 stage. Foothills 3 is the last increment in that stage area. This would translate to roughly stage 87 or 88. There's also no time limit given to complete the objective. At an average cost of 3 hours' waiting time per stage, this will take 12-14 days to complete. In-game played time will vary, depending on what you do in the game. Each stage will take 1-5 minutes to complete, so it's not too time intensive unless you actually want to play the game. I will update if this ends up crediting for me!
 
 
Here's some tips.
 
If you are playing the game to play for credit:
1) Ignore the camp portion. It's a major time sink that isn't needed to progress levels.
2) Do not replay stages for additional rewards. They don't matter, just the stage clear.
3) Brace yourself for Challenge Stages. Some are mandatory to progress, and failing them means you'll need to replay them costing you Chalices.
4) Chalices (currency to start stages) max out at 7 and regenerate 1 per hour. Stages cost anywhere from 1-4 Chalices.
5) In-game ads can grant an extra Chalice, but these are limited per day. They also appear in camp, but see 1). Do not use in-game ads for non-Chalice items.
6) Most of your time will be spent waiting for Chalices. Keep track of your maximum and try and spend down before long planned breaks (such as sleep, work, etc).

 
If you are playing the game to actually play the game:
1) Always combine items in sets of 5. You'll get 2 of the next tier, saving you one previous tier.
2) Always save Dragon/Purple Stars to upgrade them by leaving them on stages and bringing them back to camp. Tap them once before merging to maximize your yields.
3) Yields from Dragon/Purple Stars (Dragon Gems) can also be combined for more gems. There's only two levels here, so combine 5 small Dragon Gems to get 2 Large Dragon Gems and open.
4) Don't bother waiting to combine yellow/gold stars. They can be upgraded, but the yields are low for the room they occupy. Combine if you do manage to get 5, but don't sacrifice your precious space for these. There's far better uses!
5) Stone is difficult to get at the start of the game. Use it for Stone Houses only, which can produce more stone infrequently. Later, you'll gain the ability to farm stone from items.
6) Focus Stone as your first major upgrade/resource production. Dedicate room in your camp to making the highest Living Stone line you can. Stone is used for nearly everything else important (Dragon Houses, Shop Chests, etc).
7) Keep one or two high level flowers to assist in clearing dead tiles. You don't need a full garden, and you can send dragons to constantly harvest for life hearts. Don't dedicate too much room to flowers, as the upgrade chain is the longest in the game and space is a premium!
8) Prism Flowers can be harvested without dragons infrequently for life hearts. To start these, you'll need a Dead Tree that generates Necrograss. Harvest the Necrograss with a dragon, which will yield Prism Seed. Wait for the Prism Seed to grow into a Prism Flower. Prism Flowers also can be harvested for Dragon Tree Leaves, which combine into Dragon Trees which can drop Dragon Eggs and Chests. Very valuable!
9) It's better to build many Dragon Huts rather than combine them right away. Each hut has a maximum Dragon capacity, and timer. But the timers don't overlap in the higher huts and run consecutively rather than concurrently. Ex - Having 3x lv 1 Huts will give a 20 min timer on each of 1 dragon (3 total). This means you'll get 3 dragons active every 20 minutes. Having 1x lv 2 Hut will give a 18 min timer on each of 3 dragons housed. This means you'll get 3 dragons every 54 minutes.
10) Gold is relatively easy to get in camp. You can always sell items, and the blowing seeds sell for 1g each. When you first start, this is a good source of revenue.
11) Spend gold on gold huts, and like everything else - combine in lots of 5. The cost of everything increases with each purchase, so having gold huts is important to increase your maximum gold supply. Sometimes you will play certain levels that give you outright tons of gold, so you'll want the highest maximum you can afford.
12) If you have 3 or 4 of the same type of dragon egg kicking around, use excess gold to buy enough to get to 5 from the shop. The cost increases each time you do this, so wait until you get drops unless you are flush with gold.