The Heartland Mines is a challenging level with many drops to your death. The new wizard spell to cast floating platforms comes in handy. You can upgrade this to make it out of wood so Zoya can grapple onto it.
The first secret is located on a ledge above where the mine cart falls off the tracks. Inside is the Orb of Mana which increases maximum mana by 10%.
2) The second secret chest is found with potions 23 and 24. Inside is the Pendant of the Guardian which increases maximum mana by 15%.
1) Walk to the left for the first potion which is found on a wooden structure.
Put a plank on the side of the cog so you can get onto it. the potion is on a ledge at the top.
To the right of the platform elevator as it drops down. Zoya should be able to grapple onto the platform fairly easily.
4) Next to potion 2.
Inside a small wooden area below potion 2 and 3. You’ll need to enter it from below.
To the bottom left of this wooden area behind a large wooden plank.
The boards to the left of the button can be broken. Use Zoya to grapple down to the potion.
As you work your way up the area with lots of skeletons spawning use Zoya to shoot an arrow which will push the potion out of the sealed area.
The top left of the same area near the swinging spiked ball.
In the mine cart.
On a platform below where the mine cart is destroyed.
On a rock ledge below potion 11.
On the first platform on the left in the area with small cogs. Use the wizard to plank up this area and make it safer.
Continue to the right for the next potion.
On the cliff above where the wizards learns the floating platform spell. It’s a good time to put it into practice.
16) Next to potion 14.
Ride the platform across to the right and use another floating platform to reach the next two potions.
18) Next to potion 16.
19) On the rock above the two previous potions.
Hidden behind a board in the area with lots of platforms and skeletons. Use Zoya to shoot a fire arrow at it and break the boards.
To the top left of this area on top of a rock outcropping.
22) To the left of potion 20.
23) Next to potion 21.
Use the platform on a swing to work you way down to the bottom right for the next two potions and a secret.