Wind of Change

the guild redesign has already leveled things out significantly, and that is enough.

The 1st player gets the 1st Town Portal and Dimension Door, and the 2nd player gets the last one. Balance.

Making Dimension Door and Town Portal available in all schools is a great idea. And just remove Slow entirely from the 5th level :D That would be awesome.

In my opinion, anything in the game that is an absolute "no-brainer" is already not very good. If we could make an equivalent imba to Dimension Door and Town Portal (although I personally find it hard to imagine), it would be more interesting. It would also be great to give mages an equivalent imba in HotA :D

Otherwise, the idea of a strict acquisition of Dimension Door / Town Portal seems okay. And yes, 2 Dimension Doors could be limited somehow. Otherwise, some crappy level 5 Brissa flies across half the map. For example: a hero below level 15 cannot use 2 Dimension Doors. You can't cut Town Portal in any way; playing HL would become impossible.

In HotA, for instance, I think pre-built Town Portal/Dimension Door would look organic. Because the game during the 1st and 2nd weeks looks like resource gathering, while the Mage Guild often starts being built on the 1st week. After that, you choose—whether to build an army or a Mage Guild for offensive magic. Again, usage could be limited by the hero's level.