As someone who advocated making ToL Epic as the sole fix (to Temple attrition) in another thread, this change, in combination with HoB Unique (and the Gencon damage tie-breaker) seems a nerf too far.
A decision was made not to have a super-flexible arena-wide FOCUSED aggression/healing/defence vs. swarm by making HoB Unique. And I respect the decision, making the game more positional hence tactical instead of having arena-wide benefits.
This HoB decision SEVERELY limited the former power of ToL. As an interim, I'm surprised the designers did not stop there and see how this changed the meta. To add this (user-defined) activation cost to ToL makes it seem over-costed. Worse, the errata is just so inelegant. I think the "clunkiness" of this errata is what irks me most. For a game I absolutely love, and so intuitive to play. they may have marred it with this errata (the other 2 seem perfectly reasonable).
I suspect this change was preemptive, to allow for more (cheap) Temple releases in the future. If we are to get 3 new Temples of 5-6 cost, then again we have a cheaply-powered guarded Laser Lighthouse issue. If this was the reason, they should release this weaker version (superseding the original) with those new cheap temples. If future releases is the reason to nerf ToL so much (in conjunction with HoB), then it was premature. In the meantime, who would want to play the nerfed Priestess now?
I think I'm sad because all I'm seeing are moves away from control into aggro (like the Gencon tie-breaker which is even more inelegant). ToL/archers/guards was a nice zonal control concept that was different to others. There are so few "pure control" strategies. Yes, there is skill in playing aggro well but I contend there is even more skill in playing control well because it is less reliant on dice and more reliant on correctly-timed effects you impose. Control here is the correctly timed and targeted denial of mobility, aggression, mana and spells as well as removal of threats (enchantments, equipment, creatures temporarily). As someone who regularly plays control at Magic Nationals, I may be biased. But there has to be balance between these 2 polarities (there is no Combo because of pick, the other axis is Versatility vs. Focus). What the designers seem to be doing here is to move competitive play away from the more cerebral chess-like control game. Perhaps because they want to make it a Con Tournament game and control is just not that game. Which is a shame, to hobble this great game so as to make it fit within 60-90 minutes, reducing its appeal to those who like its chess qualities.
The Gencon tiebreaker decision, along with these 2 nerfs, has made Priestess uncompetitive in tournaments and it pushes players down the Route 1 "roll better dice than your opponent" aggro vs. aggro approach. Even a Wizard can't play pure control, where he trades his life resource to gain control as he will lose on tie-breaker no matter how much board control he has. He instead keeps an eye on the timer then nearing time, he spams-out his ranged damage spells (mana-to-damage efficient but not persistent) to try to catch-up on tie-breaker in what is simply a mathematical formula that tries to optimise persistent benefits vs. one-off benefits. There is simply no time for finesse.
In Magic, if you play Control competitively, you know that if you lose the first game, the best you can hope for probably is a draw. Likewise, you know that it is perfectly ok to win the match by winning the first game and not having time to complete another. There are a lot of 1-1 draws in competitive Magic tournaments. The ranking for them is decided by other tie-breakers which, over time, has been fine-tuned to be regarded as a paradigm for win-lose-draw result Swiss tournaments. This ensured balance between Aggro and Control in tournament results. There is great skill in winning a large Magic tournament with Aggro. The main skill in a game like this is adapting your play to beat your opponent's strategy. The skill required is equal to the higher skill level deck in a match-up. An Aggro player needs great skill to beat a high-skill Control deck piloted by a good player. It takes great skill to win a tournament irrespective of the sophistication of your strategies. It's just a shame that the tournament rules (and the Temples errata) promote Aggro so much.
It's not limited to Mage Wars. In Netrunner, Criminal and Weyland dominate in tournaments because they can win matches 7-0 hence win the bonus tournament prestige points. In Game of Thrones, a recent agenda and Plot opened the floodgates to Aggro wins. I'm saddened at the similar "reward Aggro" direction Mage Wars is going (maybe to make it more commercially accessible to younger age groups). This ToL errata (arguably unnecessary in the context of the HoB errata) makes one "staple" Core set control mage not tournament-competitive (in the context of the new tie-breaker) by further eroding (zonal) control in the game.
I have read the thread where a designer explains this. I just think that, in addition to HoB Unique and time-out tie-breaker announcements, to also add the ToL nerf in the current card pool just seems... excessive.
I really hope I am wrong on this.