Can we discuss how Priest got the terrible scheme spell?

I like scheme spells, but it seems that Lazul's Scheme is very weak compared to the others. All the other Schemes can really change the match. Hagatha's Scheme can destroy all the minions on the board and can even be paired with Omega Mind to fully heal your hero. Dr. Boom's Scheme can provide an insane amount of armor for your hero. Rafaam's Scheme can fill your board with imps and can be combined with other cards to buff the minions for a full strong board. Togwaggle's Scheme can put a ton of copies of a strong minion into your deck. Lazul's Scheme just reduces the attack of a single minion for 1 turn.

For me it just seems that Lazul's Scheme is very weak compared to the others. It provides no lasting impact on the board or match like the other can provide. The only good combo for the card is using Lazul's Scheme and then Cabal Shadow Priest to take control of one of your opponent's big minions. For me I feel that it should have reduced the attack of all enemy minions for a turn or make the reduction permanent.

i don't think lazul's scheme is terrible, especially compared to dr. boom's. it's even played in the best priest deck right now, nomi priest.

Lazul's Scheme is good in Chef Nomi Priest. It can also be combined with Topsy Turvy (to kill a big minion).

Some metas your class gets Entomb and instantly wins slow match-ups and other metas you get Lazul's Scheme.

It's the circle of life.

Ironically, two of the five scheme cards see no competitive play and neither of them are Lazul's Scheme, which is seen in the current most popular priest archetype, Nomi priest.  It's also the third best scheme by winrate

(0) mana is still a strategical asset in this game.

Dr. Boom's Scheme is way worse. Anyways priest is one of the weak classes at the beggining of every new year. Maybe with more expansions released the Lazul's Scheme become a strong thing against control. 

Lazul's Scheme is at last decent and can also be used as a removal in combo with Topsy Turvy. Not the best but it has some utility, even if niche.

The title of Worst Scheme I think can easily go to Dr. Boom's Scheme.

It's one of the few schemes that does see play because of Nomi priest. Being a zero cost spell is a powerful thing by itself and priest has a million ways to exploit attack reduction effects.

If anything I'd say boom and rafaam's schemes are pretty pathetic.

Late game scheme with Cabal Shadow Priest could be pretty sweet when they have a hefty minion down 

Sure, it'd be better if it reduced the Attack of all enemy minions, but it's 0 Mana. There are at least 3 situations where it can enable removal:

1. Cabal Shadow Priest

2. Shadow Word: Pain or Forbidden Words

3. Free (or, at least, less painful) trade with minions

Compare that to Dr. Boom's Scheme, which doesn't do anything that a Warrior can't already do quite well, and it's definitely not the worst Scheme.

The thing about Lazul's Scheme is that Priest is already a weak class (probably the weakest right now), with it's only optimal deck being Nomi Priest. However, in Nomi Priest, Lazul's Scheme is almost required for the deck to function. The ability to stall a big minion for one turn like a big Edwin VanCleef, enable favourable trades, cycle with Gadgetzan Auctioneer AND enable cards like Cabal Shadow Priest, Shadow Word: Pain and Forbidden Words, all for the minimal cost of zero, is pretty good. Comparatively, Dr. Boom's Scheme is seen only as a fringe tech in a mirror Control Warrior matchup, which even then isn't very effective. Similarly, Togwaggle's Scheme is a decently powerful card, but not only does it only fit into one deck (Pogo Rogue), but it also requires the player to wait a few turns for it to be an optimal play at all, AND there's no immediate value gained. Rafaam's Scheme is utter garbage, and only sees play competitively in that one Darkest Hour bullshit deck in Wild.

TL;DR, while Lazul's Scheme only serves a niche (like all other Scheme cards), in that niche scenario it's incredibly powerful. 

P.s. Hagatha's Scheme is out of the question. That card's bonkers.