Of those two methods, using Penguins to level up Phantasma is by far the easiest and most time-effective method, only needing a few clicks to execute. On the other hand, while the glory days of Dog Walking are pretty much over after the 05/27/21 update, it can still be done nowadays as an alternative if you’re running low on Penguins.
Penguins For Leveling Phantasmas
You can get Penguins mainly from the Forest of Souls by waiting for them to grow for free. But you obtain them immediately by spending some Stigma. Of course, you can also get Penguins from other sources, such as:
The Shop The Event Exchange Shop By participating in Events By clearing Adventure stages with max-level units
They’re fairly easy to farm if you know where to look.
Dog Walking For Leveling Phantasmas
Dog Walking has become a popular term in the community back, and it refers to taking the dogs (Phantasmas) out on Adventure Stages and leveling them manually. This method can also be used as a way to do Friendship Farming. But if you want to be more efficient, just take a strong friend unit or a maxed-out cleaver along with your Fodder. While this method has become less prevalent with the release of the 05/27/21 update (which allows you to get penguins for clearing stages with maxed level units), Dog Walking is still viable if you have the patience and time for it.
Where Should You Walk Your Dogs?
As a general rule of thumb, you should only Dog Walk in the highest Adventure Stage that you can clear consistently. Repeat Battling Stages is also fine, but make sure you have turned on the setting for stopping the Repeat Battles after a unit reaches max level. Also, picking up an EXP Boost in the Normal Shop will make this method a bit easier and more time-effective, although it’ll cost you around 150-300 Skystones.