I really think too many skill can take down tower without putting yourself in danger. I believe it makes the game really hard to balance. I understand that almost all DG have a damage spell so one could say it's balanced, but let's look at a couple of those.
First Uproot. I believe it should be the basis of the discussion since it's the spell whole purpose. 905 mana for 2000 dmg over 10 sec.
Now Structural Transfert. Not only does it damage but it also heal you for the same amount. One would think it's going to be worst than uproot yet it's 605 mana for a 2000 drain over 10sec. I'll also list Rook's Slam since structure can't move, he can be at point blank easily, 1700 dmg for a good 840 mana.
We have now Venom Spit. 1650 dmg over 10 sec for 950 mana. A classic on unclean beast. and with 15 range, it's almost as good as the other ranged skills
Let's not forget Regulus. I would'nt list an ability with only 1000 potential damage but since snipe can be used from the base I'd say that 1k damage for 700 mana is quite good against structures. He also can use the mines who are AoE that do 1350 dmg for 770 mana even on building; if a creep happen to be there, more money to him.
And the last but not least, Torch Bearer. The most obvious is clearly Circle of Fire. At 1500 dmg for 800 mana over 10 seconds, it's a pretty good hit and runner ability. It also has one of the biggest AoE of all the skills and unlike the mines it stick around for the whole duration so it had a better chance a getting you some extra gold and xp from a creep. Oh and between Circle's cooldown, he can throw a nice fireball for 1050 dmg each for a cheap 540 mana.
So I picked some of the skills I believe are used the most to defeat structures and I hope I'm not the only one to see how unbalanced they are.
Uproot and Structural Transfert are the only skills that can only be used against structures, I think each of them have their strength as there is no clear winner. Uproot can be used with a hit and run tactic Transfert gives back enough life to soak the tower damages. Uproot cannot be interupted but Transfert can be used on the Rook's own structure for a defensive advantage. So let's say they are more or less on equal terms.
But the thing is, while they were design as skills to kill structures, they are not the best. The basic damage spells have much more versatility. They can be used to kill other demigod, to farm creeps and are almost as good at damaging structures. Some of them even have AoE so they be can used for the three purpose at the same time.
I believe the problem come from the fact that they are pretty balanced when used on DG. But with a dedicated team of pushers, there is no way to defend yourself against a quick tower kill. They also free you some skill point because you get both a skill that can kill DG and that can kill structures. Meanwhile a QoT will have a good spell to hit your tower, but will have a hard time getting to it because she has no skill to clean the creeps or make the players fallback.
My suggestion would be to lower the damage done by the non-specialized skill against structure. I think it's the only way because we can't buff Uproot and Transfert since they are already quite good.
What do you guys think?