In Loop Hero the Maze of Memories card is a Field card, this is a type of card that creates new environmental features around or in the loop. Most Field cards spawn monsters to fight or provide some kind of bonus for the hero, and in some instances it can be combined for even more bonuses. The Maze of Memories card however is completely different, what this card does is create plenty of tiles with no effect, taking up potentially useful space with no bonuses for the hero. In order to take advantage of the Maze of Memories card you need to understand how to use it.
The boss in Loop Hero spawns once you have filled the boss meter by placing tiles. The earlier you can summon the boss the less powerful it is and the less health it has, making it easier to defeat. The longer you do not engage a boss once it has spawned the stronger it grows, it is therefore in your best interests to fight the boss as soon as possible. When you reach Loop Hero's later chapters when enemies and bosses are more powerful things will become tricky as you will want to summon the boss at the right time to prevent being easily defeated.
This is where the Maze of Memories card becomes useful, when this card is placed lots of tiles will spawn at once enabling you to summon the boss early before it has had a chance to build up its power, if you place the card early enough there is even the possibility of defeating it before the first loop is complete. Once the boss is out of the way you will be able to focus on tasks like obtaining the Astral Orb and other late-game goodies. Although the Maze of Memories card has other uses it should be saved and used strategically to defeat the boss early.
Take a look at our How to Unlock the Necromancer Class
guide to find out how to get this character in Loop Hero.