Disciples 2?

Yeap.

It is one game that was part of the Heroes 3 TBS generation . It is great because it enables saving your main hero after a mission and leveling him up in the next mission . Each faction has 5(i think) base creatures , that each can branch into multiple posibilities upon leveling up. It is a great game, great art style , that isn't entirely focused on killing the other teams' bases (because they are almost impossible to kill) but on killing a certain creature , helping a certain town do stuff.
Each faction had their type of magic resource ( 5 factions) . Like in Heroes, you got 5 tiers of magic, while the 1st tier of a factions' magic was based only on their resource, the latter needed resources from the other factions aswell , thats why a trading system was made and you can become allies and trade stuff.
I used to play it from time to time , now i miss it.
From me, with nostalgia 9/10

Yes.
Why?
The game have the same concept as heroes 3 but the gameplay a little different.Mostly for the unique gameplay.You can't capture enemy castle easy because... LOOK AT THIS so you can't beat the other player easily and you to win you must complete mission.
P.s and + to the answer from below and to NoClue too.

Disciples is indeed very similar to the heroes series but has some truly unique qualities.
Both games have turn-based battles and recourse management, though the systems are different.
The battle in disciples is more static with fewer options (not a bad thing) but with several interesting nuances which really play out well - mainly immunities/wards, which in turn leads to army composition.
Since you cant have all the units available in your castle but have to choose between overriding upgrade trees, then really have analyze which is the best unit to pick. Also, your units are very precious to you, since you have to keep them alive through out the battle in order for them to gain experience which leads more tense battles.
Leveling up your army really pays off as well, since not only do units game more hp/damage and extra abilities they also change appearance as well and the unit design is nothing short of fantastic.
Relating to unit design the whole art and music design of the game, which paints the mood for it all and I have to say - in that sense, this game is gem.
Bottom line - if you like TBS, its a must play.