7th Edition Rules: Psychic Phase

After the move phase is the new psychic phase. I won't go through all the details, but I'll give a high-level overview of this new, old piece of the game.

The number of psychic powers a psyker knows and can use in a turn are equal to his Mastery Level. But if all his known powers come from the same discipline (even if he only has one), he gets the extra Primaris power for that discipline. So even a Mastery Level 1 psyker normally knows two powers.

Unless the psyker's powers are given in his entry list, you pick which discipline you want and roll to see what power you get. A psyker's description says which disciplines he can use. Do this before the battle starts and to determine what powers he knows for the game. Disciplines are Biomancy, Divination, Daemonology (with sub schools Sanctic and Malefic), Pyromancy, Telekinesis, and Telepathy. Some army Codexes have additional Disciplines for that army. There are different levels of powers that determine how hard they are to cast. Both players know what powers you have.

At the start of the Psychic phase, roll a d6. Each player gets a number of Warp Charge dice equal to that d6 roll plus the number of total Mastery Levels of all psykers that player controls. The Psychic Phase ends when the player whose turn it us has no more Warp Charge dice in their pool. Only the player whose turn it is can manifest powers; the other player just tries to Deny the Witch. A psyker can manifest multiple powers in the same turn, but not the same power twice.

To manifest a power, select a psyker, choose a power and a target. Make a psychic test. This involves selecting a number of Warp Charge dice from your pool and rolling them. A result of 4+ means you harnessed that charge and apply it toward casting your power. You need to harness enough charge to equal the Warp Charge level of the power you are casting (1, 2 or 3). If two or more dice roll a 6 (without modifiers), you suffer a Perils of the Warp, which is similar to before ( you can take wounds, lose a power, etc., but one result can actually supercharge your psyker for the turn).

The other player then tries to Deny the Witch. He uses his Warp Charge dice from his pool to do this, just like the other player uses them to manifest powers. For each 6 rolled, you can nullify a harnessed Warp Charge from your opponent. You have to nullify all of their Warp Charges that were successfully harnessed to nullify the power. Thus, a high-level psychic power is both harder to cast and harder to nullify once it is cast. You can get modifiers to the Deny the Witch test if the enemy psychic power targets your psyker's unit. Otherwise, you need a 6.

It sounds like a lot of dice rolling, but the way I read it, the end result should be that most psyker's get to successfully cast their powers on most of their turns. The only way you will see a lot of nullifying is if one player has many more Mastery Levels of psyker's than the other or if you target the enemy's psykers with your powers. If you have an overwhelming psychic advantage like 4 or 5 times as many Mastery Levels, you can neutralize the enemy psyker pretty effectively most turns, depending on the initial d6 roll for a Warp Charge, I would guess.

Strategy to Consider: You select what order you cast powers so your opponent then has to decide how hard to try to nullify it or whether they save their Warp Charge dice for a possibly bigger power coming later that turn.
You decide how many Warp Charge dice to spend on each power. Spending more means a better chance of manifesting the power, but also a better chance of Perils of the Warp. Also, if you successfully cast a Level 2 power with 4 Warp Charge points, your opponent needs to nullify all 4 to Deny the Witch so you can make a power very hard to stop by throwing all you Warp Charge into it at the expense of casting other powers. There is never any risk in attempting to Deny so you opponent can always use all of their dice to stop you. So even if you have more Warp Charge than you need to cast your power, you may want to use extra to prevent it being nullified. You don't have to use them all.
Even if you don't have a psyker, you still get the d6 Warp Charge dice on your opponent's psychic phase (d6 + 0) so you can still try to Deny ( perhaps the vagaries of the Warp, the Daemons, or just the massed willpower and psychic energy of your forces). There will be no psychic phase on your turn.

Note: There are 42 psychic powers in the core rule book alone! Plus many more army-specific powers in Codexes, I am sure. Psychic power is truly worthy of a dedicated phase now. It almost makes me want an army with more powerful psykers (or at least a Weirdboy, something I haven't considered for my army in a long time)!