Documented for Invasion Mod 3.0.0 on Minecraft 26.3 / NeoForge. The living mob is invmod:iron_ball_mob; the flying projectile is invmod:iron_ball.
Combat profile
These are default attributes; configured base stats and wave scaling can change combat values. Movement uses its own rolling simulation, not just its 0.3 movement-speed attribute. It seeks and attacks its assigned Nexus and pursues players.
Rolling & heat
Ground steering changes direction without freely cancelling momentum. The ball accelerates gradually up to 0.6 blocks per tick on level ground, or 1.2 while heated. Descents add speed on landing, up to 1.8 blocks per tick; these gains can carry it above the ordinary acceleration limit. Climbing a step cuts rolling speed by 25%. It does not jump, keeps its launch direction while airborne and takes no fall damage.
Lava, fire and contact with a fire block heat it for up to 100 ticks (5 seconds) after exposure ends. Water or rain immediately clears the heat. Cooling reduces further acceleration; it does not instantly erase stored momentum. Fire and lava do not damage it.
Impacts
The rolling body hurts non-allied players, villagers, golems and its current target when crossing them at more than 0.02 blocks per tick. Contact damage is attack attribute × (0.5 + actual horizontal speed × 3), with stronger knockback at higher speed. It has no ordinary melee hit against living targets; the base attack value is not a fixed contact-damage amount.
A wall collision that loses at least 0.2 blocks per tick of speed triggers a compact impact blast: power is twice the lost speed, capped at 2.5. Solid blocks use one tenth of their normal explosion resistance, except unbreakable blocks and the Nexus core; fluid resistance still applies. The ball survives its own impact explosions.
When the impact center is submerged in water, the ball instead tries to destroy one block on the obstructed collision face. Unbreakable blocks and the Nexus core are excluded. Both paths respect the applicable mob-griefing protections; underwater drops follow destructed-blocks-drop. Water is therefore not a guarantee that a wall is safe.
Defense
Pickaxes avoid its damage reduction
Water cools it; drowning is lethalA direct hit from a living attacker holding a pickaxe deals its full incoming damage. Other damage is halved, except fire, falling and its own explosions, which it ignores. A positive drowning-damage event is lethal. Use sustained submersion and pickaxes; rain only cools it. Avoid downhill approaches and fire or lava defenses that speed it up.
Spawns & waves
The dedicated egg is invmod:iron_ball_spawn_egg, not iron_ball_mob_spawn_egg. To summon the living mob directly, use /summon invmod:iron_ball_mob ~ ~ ~. No vanilla mob is replaced by it.
It is active by default as a non-boss wave entry costing 10 in FAST and MIXED, and is also eligible for RANDOM and RANDOMHELL, whose non-boss price is 5. It can therefore fit the budget from wave 1, but a random purchase is not guaranteed. Themes and entity settings control selection.
A Piglin Thrower launches the separate invmod:iron_ball projectile. After its power-4 explosion, it creates a living ball if collision-free placement is possible at or above the impact position. That ball inherits the thrower’s Nexus link. This additional spawn is distinct from buying a ball directly for a wave.
Drops
See IM display names. Use the registry IDs listed in the mob guides.
The default loot table drops one Iron Block. The inherited IM death-loot hook also has a 25% chance to add one Small Remnants.
Iron Block • 1
Small Remnants • 25%