I would say that the unfortunate answer that I usually give is “it depends.”
For most people, no, it’s not worth it. For some people and with some heroes, I think the benefit could help bridge the gap between effectiveness and usability depending on their goals and long-term plans with the game.
Here were the maths I did in another thread: Is it useful to bring a hero that's worth upgrading, to tier 20 completely? - #11 by MD-DC I didn’t look at Very Fast heroes because I don’t have any.
Basically, there are break points one needs to get to for the mana troops/boosts to have any tangible benefit from the offense in terms of tiles.
For most practical purposes, fast heroes never gain a benefit (going from 8 to 7 tiles) barring Rob_DI’s experience earlier in this thread which is a bit of a corner case. This is because in a match-3 game, in most instances they have to be multiples of 3 to gain a practical benefit and since one is generally going to have to make 9 tiles anyway in most circumstances, so whether or not you gain that one tile benefit for a fast hero is irrelevant in most situations. Sometimes in a few corner cases it will matter, but the majority of the time it won’t because you were already winning or losing anyway. The same goes for Slow heroes who go from 12 to 11 tiles because, once again, you’re still going to generally have to match 12 tiles anyway, so that tile benefit makes no difference since the extra mana is lost if the hero is already at max mana.
So for most people, the only real benefit is going to be an average speed hero who goes from 10 tiles to 9 which is a very significant break point since this means that they functionally charge at the same rate as fast heroes. So instead of having to make a 12 match to charge most average heroes, you only need to make a 9 match which is the difference of one turn which early in the game WILL matter. In order to meet this break point, one needs to get a total of +13% mana generation.
Now that said, the caveat must be made that over time, the heroes will fall out of sync. This is more relevant in challenges, events, and Titans where the match goes on long enough to matter. In raids, wars, and tournaments, one doesn’t always have the time for this to make a difference. Over time, the one(s) with the mana troops will charge faster, and the average hero will fall out of sync with the fast heroes. But for the critical initial turns of a raid/war/tournament, they’re functionally identical.
I don’t consider hero ability mana generation to be relevant because heroes like Alberich, Misandra, Ariel, Khagan etcetera are not active in the initial first few turns and never will be. It will matter in the long run, so they’ll be more useful for Titans and events, but for raids and the like, the ability can basically be ignored. If you’re at a point where you’ve activated said hero, you’re probably already winning. For tight matches, it will matter, but tight matches are rarer than blowouts, one way or the other.
SO the key question for a person to consider is:
- Would this particular, average speed hero make a critical difference activating a turn sooner? Examples of heroes where this is more likely to matter are Rigard, Kiril, Boldtusk, and Wilbur. Heroes where this is less likely to matter are Cyprian, Kashhrek, Sabina, and Thorne.
- Do I have the emblems to get them the +2% mana speed boost? Paladins get that at +19, and if your Thorne is nowhere close to that, the question is not relevant.
- Do I have a corresponding mana troop that’s level 11/17 (Monks, Sorcerers, and Druids get +4% mana gen at +20)?
- Do I have a mana troop at level 23+?
If a player does not have critical, game-changing heroes, the investment is a bit of a waste. If a player does not have mana troops at least at level 11 or 17 (depending on hero), this is a bit of a waste since the node provides no practical benefit. If the player already has a mana troop level 23 or higher, this is unnecessary since the mana troop provides the breakpoint mana gain by default regardless of talent nodes, and the additional +2% mana gain basically makes no difference.
So for most people, no there is no benefit. But in a few specific instances it would matter.
That’s why I got/kept the mana nodes for Rigard, Wilbur, Merlin, and Sabina, and for matches where I think it will matter (versus enemy Gravemaker, enemy Wilbur, enemy riposte for instance), I make sure they have the mana troop. For everybody else (Caedmon, Chao, and Sonya for example), I pretend it doesn’t exist. I did not get them for Boldtusk (I have no snipers for him to synergize with and usually bring Ares anyway, so the point usage is better served elsewhere) or Kiril (he’s either part of an average-speed combo with Frida, Richard, and/or Grimm and doesn’t have the Wizard emblems to get to +19 yet anyway).