So I really loved TDS for its subtly fresh, but yet nostalgic feeling. It was essentially the same thing as playing 'real tibia' but with a few neat enhancements and a brand new map (which by the way was amazing). The problem is - it has lagged behind quite a lot. Most servers you can play now have all those neat things that were rather rare at its time, at least to have working so well.
If the server is to come back, it needs to improve in at least one of the following areas:
Quests
There were achievements giving experience. That's it. It was fun in the beginning (1-100), and a nice experience boost above that, but nothing "cool" to be honest. There was a really old trailer about some massive maze - something like that is desperately needed. Fighting the final boss on TDS was fun, but it was in no way an epic quest experience. Lower tier quests also needs a bump, all I can remember was a few chests 'hidden' around in spawns.
Spells
Spells are fairly easy to add if you keep them simple, the only ones that were special were the "blood sorc" ones, and I guess creating assassin stars. They can be made a lot more intricate with things added in like knockbacks, stuns and silences - but as I recall you didn't really have a dedicated scripter willing to actually implent new things. Do you now?
Crafting
Most rpg servers now have some sort of crafting system, and I think it's almost essential to be able "compete" today. It's often very simple - mine this, magically use this item on it and poof you have a weapon. Some servers have evolved it much much further, Necronia being a prime example.
Weapon enhancing/rare loot
Back in the day TDS had (one of) the best system, where you could both loot things giving you better drop% or different damage elements, or even runes that you could mix and match yourself. This system is still good, but could use a lot of improvement. (read: disparity)