Rocks and Mountains are a combo deal, you cannot have one in your deck without the other, so its no surprise that the two work in tangent on your expeditions.
As far as basic synergy goes, Mountains give you +2% of base HP for each adjacent Rock or Mountain. Similarly, Rocks gives you +1% of base HP for each adjacent Rock or Mountain.
However, there is a greater combo here when you combine a mixture of Mountains and Rocks together in a 3×3 square as they will then transfer into a Mountain Peak which will give you the following:
- +120 HP
- +5 HP for each adjacent rock/mountain title.
There is a slight downside as having a Mountain Peak will also spawn a Harpy once every 2 days. Note you can only have one Mountain Peak per expedition.
Meadow/Any Other Tile Into Blooming Meadow
Blooming Meadows are created whenever a Meadow is placed next to another type of tile (any non-Meadow tile). Blooming Meadows heal for 3HP as opposed to Meadows which only heal for 2HP, so to maximize the effect you get out of your Meadows, it is best to place them adjacent to another type of tile.
Village and Vampire Mansion Into Ransacked Village/Count’s Land
A Ransacked Village is created whenever a Vampire Mansion is placed adjacent to a Village title. Ransacked Villages can spawn up to 4 Ghouls once per loop. They will also turn into Count’s Land tiles after 3 loops.
Count’s Land tiles heals [15+5*loop] HP upon entering and will give you a quest with a better reward than that of a normal Village tile.
Blood Groves Into Hungry Groves
Blood Groves can be transformed into Hungry Groves through a number of methods. If the Blood Grove is only surrounded by Burning Forest tiles (covered in the next section), then it will transform into a Hungry Grove. Alternatively, if you use an Oblivion card to destroy all adjacent Grove/Forest/Thicket tiles, the Blood Grove will turn into a Hungry Grove.
Hungry groves can occasional attack the Hero for [5+3*loop] damage, but will also kill any foe with less than 20% HP remaining.
Forest/Thicket and Storm Temple Into Burned Forests
Burned Forests are created whenever a Forest or Thicket tile is struck by lightning from a Storm Temple. Storm Temple’s will strike lightning on 2 random tiles in its range every 5 seconds, so it shouldn’t take long for your Forest or Thicket tiles to transform into Burned Forests if they are within range.
Burned Forests gives +0.5 Magic damage and can be used to create Hungry Groves as shown above.
Treasury Into Empty Treasury
Once you complete a Treasury by filling in all 8 tiles surrounding the Treasury, it will empty and give you a load of resources and equipment. The quality of the equipment you receive scales with the loop you finish the Treasury on, so it is better to complete a Treasury on a later loop.
River and Desert/Sand Dune Into Oasis
Whenever you place a River next to a Desert or Sand Dune, the River will turn into an Oasis. Oasis tiles -0.5% to the hero’s attack speed, but also -1% attack speed to all other creatures so the positives outweigh the negatives.
River and Battlefield Into Shipwreck
Whenever you place a River next to a Battlefield, the Battlefield title will transform into a Shipwreck which will give you a chest once per loop, but will also spawn a siren once per loop. It also keeps the Battlefield’s effect of having the potential to turn enemies into ghosts on adjacent titles.
River and Wasteland Into Bridge OR Reed
There are two final synergies for the River, both involving Wasteland tiles. If you place a River onto a Wasteland tile, the tile will turn into a bridge, allowing the river to flow through the title.
If you place a River next to a Wasteland tile, the River will turn into a Reed which spawns a Fish Man every 3 days.
Suburbs Into Towns
When you combine 5 Suburb tiles in a cross (+) pattern, the middle tile will be transformed into a Town. Towns add +2 to experience gained from killing enemies.
Battlefield and Wasteland Into Blood Path
Any wasteland within a Battlefield’s range (the 8 tiles surrounding where the Battlefield was placed) will turn into Blood Paths which spawn a Blood Clout every 4 days.
Abandoned Bookery and Vampire Mansion/Temporal Beacon
If you place a Vampire Mansion next to an Abandoned Bookery, it will spawn a Vampire Mage in each fight in the area. If you place a Temporal Beacon next to an Abandoned Bookery, it will spawn a Time Watcher Mage into every fight in the area.
A Village? and Wheat Field Into Overgrown Field
Place an A Village? tile next to a Wheat Field to turn it into an Overgrown Field. Alternatively, you can also create an Overgrown Field by using an Oblivion card to destroy a Village adjacent to a Wheat Field.
Overgrown Fields spawn a Scarecrow every 4 days and creates a Field of Blades on empty tiles during Combat.
Goblin Camp and Swamp Into Goblin Lookout
If you place a Swamp next to a Goblin Camp, the Goblin Camp will transform into a Goblin Lookout which adds a Goblet Archer to battle.