RTF is a global modification that replaces all towns in the game.

It seems he will have poison.

Added 1 minute ago

It won't be soon; I still need to create a town, heroes, a couple of creatures, and redraw the specializations.

Added 30 seconds ago
Will the spiders be alive?

The undead will be released in a simplified version - creatures without a castle and with a few heroes, but it will still take some time before the release - the creatures only have visuals without icons and other enhancements.
The unupgraded spiders will be alive, and the upgrades will either be undead or servants of darkness.