I understand that the majority of the posts on the internet classify the Echo Knight as an object and not a creature, including this post. However, does that preclude the Echo Knight from being affected by all spells or effects that specify “creature”? Fireball, for example, reads in part, emphasis mine:
A bright streak flashes from your pointing finger to a point you choose within range and then blossoms with a low roar into an explosion of flame. Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 8d6 fire damage on a failed save, or half as much damage on a successful one. The fire spreads around corners. It ignites flammable objects in the area that aren’t being worn or carried.
Another example is fire shield as stated in part below, emphasis mine:
In addition, whenever a creature within 5 feet of you hits you with a melee attack, the shield erupts with flame. The attacker takes 2d8 fire damage from a warm shield, or 2d8 cold damage from a cold shield.
My final point of contention is the DMG pg 246 states
For the purpose of these rules, an object is a discrete, inanimate item like a window, door, sword, book, table, chair, or stone, not a building or a vehicle that is composed of many other objects.
My personal feeling on this is that I have a very hard time believing that the Echo Knight is immune to spells based on creature vs object language, yet it can still be commanded as if it were a creature.
