Nice map, it has good basics, and well some things could be improved.
1) Some areas seems to have narrow path, when armies collides, heroes can be trapped with no escape, and the blademaster is very good for narrow battles.
Sugestion: try to make the path, delete wood and water for that, is better to have 1 wide path than 2 path narrow. For my experience 7-8 pixels wide is what I usually wish in my maps but is a sugestion.
2) The murlocks in the water, I think the ramps should be a bit wide,
I sugest 2 pixels more wide, since it will be a melee battle, so units will have space for that.
3) to much land critters gives advantage to the necromancers in competitive melee play,
Sugestion: use land critters near creeps that don´t leave corpses, like golems, skeletons, , ghosts, aereal units, if not, only use air critters and avoid the use land ones.
4) Items loot
There are no loot for permanent level 1, while some permanent level 2 and 3 are buyable items in the market.
You have a gnoll creep level 11 camp in the edges looting permanent level 3 while you have a pandarem creep level 12 looting a permanent level 2
Sugestion, make the gnoll camp green and loot 1 permanent,
the polar bear creeps level 12 loots permanent level 3,
Also the furbolg elder shaman level 18 loots a permanent level 3
Sugestion make the polar bear level 12 loot the charged level 2 instead
as it is 3 creeps of diferent level looting permanent level 3 wich some of them are buyable in the goblin markets, is redundant and also you loose item diversity ( charged level 2 and permanent level 1 could be in the map)
Also for the level 18 market creeps, setting the level 2 power up manually I think it will be more acurate for a level 18 creep.
As overall is a very good map, I think the important things that could be improved are to make more wide path (sacrifice wood and water for that), and the loot can be better.
Rating 4/5
see ya