Destiny 2 Warlock BuildSong of Fire and Ice

• [Most Preferred Method] Toss Bleak Watcher in a swarm of enemies or on top of a miniboss/boss. The Stasis Crystals spawn and Freeze enemies, leaving both the Stasis Crystals and Frozen enemies completely open to Ice Breaker shots. This is especially great against Overload and Unstoppable Champions.

• Alternatively, toss Bleak Watcher near you to also gain the benefit of icicles that Slow enemies from Rime-coat Raiment. You can also plant a Healing Rift here to proc healing if necessary. You can also shoot the Stasis Crystals to proc Shatter and Ignitions if enemies decide to approach you.

Ice Breaker: This will be your main source for proccing Shatter and Ignitions, which deal incredible damage when combined. If you're unable to get a Bleak Watcher out, Ice Breaker shots can easily take down red bars and put the hurt on orange bars.

• No Backpack: Since you'll be taking advantage of Shatter and Ignitions, they'll generate ammo directly back into the weapon. If you run out of Ice Breaker ammo, then you can freely use your other weapons or abilities to generate some more.

• Ice Breaker (Trait): Body-shot final blows cause an explosion similar to aFirefly; but precision final blows or shattering Stasis Crystals and Frozen enemies trigger Ignitions.

• Ice Breaker Catalyst: Shooting at Slowed or Frozen enemies has a chance to return the round to the magazine, thus feeding more into ammo generation.

• Song of Flame: Mainly used as an emergency "get-out-of-jail-free" Super to escape heated situations, or if you're out of ammo/ability energy. Final blows with Song of Flame can also generate ammo for Ice Breaker.

• Transcendence: Mainly used an an emergency install to quickly regain ability energy if necessary, and/or Orb generation due to Facet of Generosity (mentioned below). Bleak Watcher can easily generate constant Darkness Transcendence energy, and Ice Breaker shots and Ignitions can generate Light Transcendence energy.

• Healing Rift: Mainly for team support and if you decide to toss a Bleak Watcher at your location for additional healing. Ultimately, the choice for Class Ability is up to you.

• Burst Glide: Best Glide.

• Incinerator Snap: Mainly used for Light Transcendence energy generation and enemies within close proximity in a pinch.

• Healing Grenade: Mainly used for emergency Cure and Restoration for you and allies in a pinch. Otherwise, convert to Bleak Watcher.

• Bleak Watcher: The BREAD of this build. Convert your grenade to Bleak Watcher to Slow and Freeze enemies, setting them up for Ice Breaker.

• Feed the Void: Shatter and Ignitions proc Devour, and can easily be maintained with the general gameplay loop.

• Facet of Devotion: Enemies are constantly going to be Slowed or Frozen, allowing you to compensate for the lack of Light Transcendence energy generation.

• Facet of Awakening: Ignitions and Shatter will take down rank-and-file enemies (red bars) and majors (orange bars) easily, allowing Firesprite and Stasis Shard generation for additional Grenade and Melee ability energy.
• Facet of Generosity: Transcendence is mainly used for Orb generation and/or regaining your abilities back in a pinch.
• Facet of Ruin: Enhanced Shatter and Ignitions. This is a MUST for this build.
• Facet of Purpose: Every Prismatic build should use this Fragment, which in this case grants Restoration when picking up an Orb of Power.

Additional Note: Facet of Courage does not buff subclass verbs (as far as I can tell).

Kinetic Weapon Slot: I would suggest using a weapon that has Shoot to Loot if you're ever in need of picking up a Special Ammo brick from afar if your Ice Breaker is running low or doesn't have ammo left. Otherwise, the choice is up to you. A Kinetic Weapon may also be good to offset the lack of Light Transcendence energy generation. A Stasis Weapon with Rimestealer and Headstone may also be good, but Frost Armor is meh without going all in on Shadebinder with its enhancing Fragments.

Heavy Weapon Slot: I would suggest a Solar Heavy Weapon to offset the potential lack of Light Transcendence energy generation. Ultimately, the choice is up to you.

Helmet Mods:

• Solar Siphon x3: With the constant proccing of explosions and Ignitions from Ice Breaker, you can easily and quickly generate Orbs of Power for you and allies.

Arm Mods:

• Momentum Transfer: Bleak Watcher bolts/bursts count as Grenade damage, which feeds Melee ability energy.
• Impact Induction: Incinerator Snap can contribute to Grenade energy.
• Bolstering Detonation: Same as Momentum Transfer, Bleak Watcher can feed into Rift energy.

Chest Mods:

• Pick whatever resistances you'd want depending on the activity.

Leg Mods:

• Recuperation: Due to the potentially high number of Orb generation, they can be used to heal in a pinch.
• Invigoration: If you're unable to throw a Bleak Watcher, the Orb generation can help feed into Grenade energy if needed.
• Solar Scavenger: Since I recommended using a Solar Heavy, this will help with its ammo. If you're using any other element, then switch accordingly. Alternatively, you can swap this mod out with any other Leg Mod if you want.

Class Item Mods:

• Outreach: Rifts can feed into Melee ability energy.
• Powerful Attraction: Rifts can collect nearby Orbs in a pinch, if necessary, and also build Armor Charges.
• Utility Kickstart: Rifts consume however many Armor Charges you have to feed back into Rift energy.