Phyrexia: All Will Be One is a return to Magic: The Gathering's plane of New Phyrexia in over a decade. There are plenty of powerful cards in the set with a ton of strong effects that can be very easy to cast.
The enchantment lineup in Phyrexia: All Will Be One is powerful as well. There are plenty of cards that enable a ton of strategies and, in some cases, can enable incredibly strong combos capable of winning the game in just one turn. The power level of the set is quite high, making for a collection of powerful enchantments.
7 Maze's Mantle
Maze's Mantle is a unique protection card that can give hexproof to your creatures with toxic. Otherwise, it gives you a creature a simple stat boost. Since there are plenty of strong cards with toxic in the set, Maze's Mantle can give protection to a lot of your powerful win conditions.
Since creatures with toxic still deal regular combat damage, Maze's Mantle can make the toxic creatures with trample even more threatening. It also ensures that your combat damage goes through to trigger toxic trivial. Since so long as at least one damage gets through, toxic will trigger, so boosting up stats to ensure you hit the life total is very strong.
6 Necrogen Communion
A solid enchantment for decks that can run it, Necrogen Communion is a great card. It gives the creature pseudo-protection, as when the creature dies, it gets to come back to the battlefield. This makes removing it much harder. You can enchant a powerful, high-mana creature to make your opponent remove it twice.
Not only that, but as an added bonus, it gives the creature toxic two, which puts the opponent on a time-clock to destroy it before you deal damage to them five times, as they will lose through getting ten poison counters if that happens. It forces your opponent to use removal on it or risk losing to it.
5 Planar Disruption
Planar Disruption is one of the best 'Pacisim-like' effects, namely due to how many targets it can hit. Planar Disruption is an Aura that can shut down creatures' abilities and capability to attack, but more notably, artifacts and planeswalkers. Both card types generally have activated abilities, meaning they essentially become useless.
Against artifact lands, Palanr Disruption can prevent them from being able to tap for mana, as tapping is an activated ability. It can severely hinder planeswalkers, which become useless if Planar Disruption is put on them unless they have a passive ability. Some colors, such as red and black have a lot of trouble removing enchantments, so against certain decks, Planar Disruption can shut them down entirely.
4 Skrelv's Hive
Skrelv's Hive is a card that gives you a toxic token on each upkeep. It gives you the added bonus of giving creature tokens lifelink when an opponent has three or more poison counters, something that can be easily done with Skrelv's Hive itself. In constructed formats, cards that make a token each turn tend to be strong, and even though the tokens from Skrelv's Hive can't block, the toxic ability often makes them need to be blocked.
Skrelv's Hive even gives you survivability as the game progresses. Since your tokens gain lifelink once you give someone three poison counters, they can start healing you to make it harder for your opponent to come back from.
3 Phyrexian Arena
For the first time since 2005's Ninth Edition set, Phyrexian Arena will be Standard-legal, and thanks to that, enter Pioneer/Explorer legality as well. Phyrexian Arena is a powerful enchantment that helps black decks draw cards, giving you an extra draw at the start of your upkeep at the cost of one life. While this can accidentally deal an uncomfortable amount of damage, cards like Sheoldred, The Apocolypse can help counteract it while doing damage to the opponent.
Phyrexia Arena has a fairly low casting cost as well, allowing you to get it down on the battlefield early to start taking advantage of it right away. It still requires you to be careful with it, as it is not uncommon for Phyrexian Arena to wind up burning you for lethal burn damage directly to you.
2 Ossification
A powerful removal spell in white, Ossification lets you take care of any creature or planeswalker. Instead of enchanting a creature, you enchant a basic land, and that card stays exiled until Ossification leaves the battlefield. Since it has to be a basic land, Ossification is much safer, as removal for basic land cards is much rarer.
Ossification is hard to remove outside of dedicated enchantment removal. Since it can hit creatures or planeswalkers, the versatility it provides compared to something like Chained To The Rocks, which has a similar effect, makes the card better to run a lot of the time. Even though Ossification costs one more mana than Chained To The Rocks, the land it can enchant is broader, less prone to removal, and able to hit planeswalkers when they are frequently played.
1 All Will Be One
The card with the same name as the set, All Will Be One is the strongest enchantment in the set. There are many ways to break the card, as its effect is not once per turn. So if you have a way to continuously put counters on a creature, you can deal an infinite amount of burn damage to either creatures or an opponent's life directly.
Since it deals damage, All Will Be One can go infinite with cards like The Red Terror and Night Dealings, as they get a counter whenever damage is dealt to a player or permanent, which will then cause All Will Be One to trigger again, creating a loop that can do infinite damage. If you have a Soul-Scar Mage on the battlefield, it can even act as a one-sided board wipe as it will put a -1/-1 counter on it instead, which then causes All Will Be One to trigger to do this to every creature on the battlefield you want off the battlefield.