Optimizing your Warp Charge

Here are some tips to help you when casting your psychic powers. As an example my current list I'm running has two level 2 psykers:

Rune Priest - Divination (psychic hood & ward)
Librarian - Telepathy (psychic hood)

This is a total of four warp charges. Doesn't sound like a lot but even against armies with a lot more such as Daemons, Grey Knights and Tyranids which can all have 10 or more warp charges I can often successfully cast my psychic powers. It's important to note that statistically for a blessing your opponent must roll six dice for each 4+ you roll... So often if you can manage to cast three or more 4+ on a blessing your opponent needs 18 warp charges on average to deny it. Sure sometimes the opponent gets lucky - it happens but it's not commonly occurring. I think of this as optimizing my psychic phase... While I've only got 4 warp charges plus the d6 at the beginning of my psychic phase if I roll well I can succeed.

Casting
It's important to rank your psychic powers knowing which are most important to cast. A trick is to cast a malediction requiring one successful warp charge first to draw off some of your opponent's warp pool so they have less to deny with when you attempt to cast a blessing such as the Much hated Invisibility. So for example I attempt to cast Psychic Shriek first which only requires one warp charge then I roll for Invisibility having drawn off some of their warp pool.

I will typically roll 6 dice to cast a level 2 psychic power, again such as Invisibility... It's a game changer and well worth the risk. If you roll 6 times you should on average succeed three times thus requiring your opponent needing 18 dice on average to successfully deny it - most armies won't have 18 dice, especially if you can draw some off on a lesser spell first. Rolling 5 or less dice greatly diminishes the odds in your favor. In my opinion it's better to be bold and risk a perils for the best odds.

Denying
Each of my psykers have level 2 mastery plus the Rune Priest has Ward which is equivalent to Admantium Will. My Chapter Master has the Shield Eternal which also confers Admantium Will for backup. My two psykers are both joined to the same unit as the Chapter Master which means I'm denying on a 4+ versus 6+ against any malediction cast against the unit. Most often I'm able to successfully deny these maledictions which can also be quite a game changer versus powerful psychic maledictions such as Paroxsym or Shriek. I also have the psychic hoods so my psykers can deny for other friendly units up to 12" away. I like having two hoods for backup in case I lose of my psykers.

Combinations
The psychic powers you get are random. That's said you'll want to find combinations for the synergy. By using two spells in tandem the overall affect can be much more powerful. For example during a game versus Salamanders with an Imperial Knight I had Foreboding and Prescience amongst some other psychic powers. I was able to successfully cast both anticipating a charge from the enemy Knight targeting my super friends unit including the two attached psykers. Foreboding lets you fire Overwatch on your full ballistic skill plus counter attack and Prescience lets you re roll missed hits. Turns out I was able to strip two hull points and concuss the enemy Knight. I then destroyed the Knight in one turn of melee.

Prescience and Misfortune are a great combo versus enemy flyers. I play a biker army and had a recent game versus an army with three Stormravens loaded with assault cannons, hurricane bolters, missiles and multi-meltas. Misfortune is a malediction that cause all attacks to be rending. This combined with twin linked bolters is a great way to force flyers to jink and even destroy them.

Terrify combined with Psychic Shriek is another great combination. Look for the synergies.