Summon Minion is a bonus used by Unique Monsters. This ability allows them to summon Baal's Minions. All main quest and Helliquary bosses in Diablo Immortal have this skill that enable them to summon specific monsters as minions.
Damaging Skills
Fire — Embers • Eruption • Fire Arrow • Fireball • Fire Bolt • Fire Hit • Firestorm • Fire Wall • Flame Circle • Grenade • Hydra • Incinerate • Incineration Nova • Inferno • Meteor • Minefield
Ice — Arctic Blast • Blizzard • Cold Touch • Fire Hit (Cold) • Freezing Charge • Glacial Spike • Hoarfrost
Poison — Poison Bolt • Poison Breath • Poison Cloud • Poison Spit • Poison Spray • Poison Sting • Poison Strike
Lightning — Lightning • Lightning Arrow • Lightning Globe • Lightning Storm • Red Lightning Hose • Shocking Hit • Spark Defense • Thunderbolt
Physical — Bite • Blast Wave • Blow Dart • Charge (Berserk Charge) • Cleave • Corpse Cannon • Destructive Strike • Divebomb • Grab • Ground Spikes • Ground Tentacle • Leap • Javelin • Leech-life Ball • Pummel •Quake • Quill Dart • Slam • Snatch • Spine Dart • Strike • Swipe • Sweep • Whirlwind
Magic — Beam • Blade Beam • Blast • Bomb • Bone Spirit • Hellish Projectile • Nova • Tide • Tornado • Torrent • Unholy Bolt
Non-damaging Skills
Indirect Attack — Blood Mana • Curses • Mana Rift • Minion Frenzy • Putrify • Spin Web • Stun • Vortex
Spawning — Bone Prison • Festering Appendages • Lay Egg • Minefield • Mystifying Growth • Revive • Summon Minion • Totem
Self-effect — Bone Armor • Burrow • Effigy • Fly • Frenzy • Heal • Shell • Teleport • Vile Effigy