Nature Structures

Good plan, but there are a few points to consider:
1) You slightly underestimate the neutral archers.
2) Usually, these neutrals consist of infantry and archers.
3) By the time you have enough Water Elementals, Elves, and Griffins (which need to be built), there will be many neutrals, and they will overwhelm you with numbers. 1 Water Elemental deals 65 damage with lightning and 37 damage in an area.

We have an answer to this - yes, if you only have one Castle, Water Elementals might not be enough, but in this case, I first max out summoning magic, even if there are Griffins in the group; Water Elementals are still replenished daily. And considering that through the portal, their weekly increase is 10, it turns out that 17 elementals arrive per week. Of course, it's difficult with neutrals, but if you bring reinforcements in time, you can leave without losses. In this situation, the Water Elemental's Fireball spell is very helpful - at least reducing the number of archers by half, and also reducing it for 2 squads at once. And if you can upgrade the hero's Death magic and demonology, then by summoning devils, you can block one archer squad, and the other two will switch to attacking the devils.
As for the infantry, most of them won't reach the front lines in 1 turn; I will have time to push them back. Meanwhile, the hero will use the quicksand. And from the 2nd turn, the elves will deal with melee fighters, and we will send a Fairy, as it has no retaliation. In the worst case, we'll use Wolves and Griffins.