- Goddamned Bats: Although the units stated below can be obtained by the player later on, the first few times the player encounter them would bound to delay your advance at best and outright force you to reset the game at worst:
- The airborne-mermaid-thing can put units into sleep efficiently and two of them using the same sleep attack on the same unit will mostly render the unit fully sleeps, which immobilizes the unit and preventing them from attacking. And the skull-headed version can actually attack units with high attack power on top of the sleep spell being upgraded.
- The medusa is like the airborne mermaid, except that it inflicts petrify which is permanent unless being cured.
- The genie and the air dragon, despite being an air unit, are extremely tough, deal significant damage to most land units and most anti-air attacks are inefficient against it.
- The land dragon is even worse. It is immune to lava damage (which actually gives terrain bonus), can stock up to 16 attacks (most units get 10 at most) and not even the genie and air dragon are efficient against it.
- The octopus and giant fish are naval monsters similar to the genie. Both are extremely tough on sea and the former has anti-air attacks. For the latter, thanks to geo effects not even the genie and air dragon above are efficient against it.
- The ranger, priestess and samurai has powerful range 3 attacks while other units get attack range of 2 at most, which means they can strike units from afar first. Their primary attacks are anti-air as well.
- The phoenix is completely untargetable once they used up their only attack, which then generates more mana than the mana generator units and can be repeated indefinitely, which allows other units stated above to be spammed almost constantly. The only saving grace is that they do not count as units when said attack is used in determining the kill all enemies win condition.
- That One Level:
- Map 8. This is the first map where the opponent has pre-captured mana crystals, range 3 attacking rangers and mana generator units, in addition of cliff terrain that only air units can cross. The mana crystals are placed across waters where it shall slow down mana crystal capture the first time the player can access it. Worse yet, the AI are smart enough to send units to step onto the summoning circles which prevents units from being summoned. There is absolutely no room for mistakes in this map.
- Map 11. The enemy is at the top of a cliff, the AI always spam mana generator units to gain a quick mana pool lead and the units sent down to the player are mostly priestesses or genies (see the above), which prevents the player from getting near to the enemy's area without having units severely damaged.
- Map 20. The enemy starts the map with three land dragons which charges towards the player's castle and turning most of the fields into lava! This map is unwinnable without the phoenix unit and even with it the map is still very hard thanks to the lava fields which renders most land units vulnerable.
YMMV / Genjuu Ryodan