Doomcaliber Knight

Edison Card Text
Ⓢ Cannot be Special Summoned.
① If a monster effect is activated (Quick): Tribute this face-up card; negate the activation, and if you do, destroy that monster.
No targeting
No Damage Step effect
Banlist • Unlimited
Interactions
What happens when The White Stone of Legend is discarded for hand size?✓
Player A discards The White Stone of Legend for the end-of-turn discard.
Its mandatory Trigger Effect must activate. You cannot chain Super Rejuvenation from hand to this effect. Spell Speed 2 effects can only be chained here if they negate activations/effects (e.g., Divine Wrath), and Spell Speed 3 effects can always be chained. If either player controls Doomcaliber Knight, its mandatory Quick Effect immediately chains and Tributes itself.
How does Doomcaliber interact with Treeborn?✓
Treeborn activate while Doomcaliber is face-up.
Treeborn has no once-per-turn restriction, and Doomcaliber is mandatory so it must negate it by tributing itself. Treeborn Frog can then Special Summon itself
Rulings
edisonformat.net
● This effect is Mandatory. It can (and must) activate in any Step and any Phase,
including Damage Calculation, and even in response to a effect triggered by an End Phase discard.
● If 2 "Doomcaliber Knight" are on the field, when a monster effect is activated,
both are tributedm, and both "try" to negate that monster effect.
however, only the one with a Chain Link directly adjacent to that monster effect in the Chain
(the first to activate) will actually negate that Monster Effect.
edisonformat.com
(C) This card cannot be Special Summoned. (1) When an Effect Monster’s effect is activated, you must Tribute this card. Negate that effect’s activation, and destroy the monster.
The (C) Condition cannot be negated.
The (1) mandatory Quick Effect MUST activate whenever its activation requirement is met.
This effect will even activate during the Damage Step, even if "Doomcaliber Knight" is destroyed by battle and an Effect Monster's effect activates in any Substep after Substep 4 - Damage Calculation.
Tributing this card is a cost. This effect CANNOT activate while "Mask of Restrict" is active.
This effect will negate whichever monster effect preceeds it in the chain, even if that effect would do nothing (ex: "Magician of Faith" is Flipped while that Player has no Spell Cards in their Graveyard).
Example 1: Player A Tributes their "Sangan" to Summon "Zaborg the Thunder Monarch".
Chain Link 1 = "Sangan", Chain Link 2 = Zaborg, and Chain Link 3 = Doomcal. Thus, Doomcal will negate and destroy Zaborg, and Sangan resolves successfully.
Example 2: "Blackwing - Blizzard the Far North" is Normal Summoned while "Black Whirlwind" is active.
If Chain Link 1 = "Black Whirlwind", Chain Link 2 = Blizzard, and Chain Link 3 = Doomcal, then Doomcal will negate Blizzard's effect and destroy it while "Black Whirlwind" resolves without effect.
If Chain Link 1 = Blizzard, Chain Link 2 = "Black Whirlwind", and Chain Link 3 = Doomcal, then Doomcal will resolve without effect but Whirlwind and Blizzard will resolve successfully.
If multiple "Doomcaliber Knights" are face-up on the field, and a monster activates its effect: they will all Tribute themselves as separate chain links, however, only the Doomcal chained directly onto that monster effect will successfully negate that effect.
Example: Player A controls 2 "Doomcaliber Knights". Player B activates an Effect Monster's effect. Both of Player A's "Doomcaliber Knight" activate and form a Chain:
Chain Link 1 = Effect Monster, Chain Link 2 = Doomcal A, Chain Link 3 = Doomcal B
Only "Doomcaliber Knight" A negates the Effect Monster's effect.
VS. "Kuriboh": If an attacking "Doomcaliber Knight" is Tributed to negate "Kuriboh's" effect, then damage has already been calculated. If "Doomcaliber Knight" was attacking a monster with equal or lower ATK that monster will be destroyed, and Battle Damage will be inflicted as normal.
Example 1: Player A Tributes her "Sangan" and "Witch of the Black Forest" to Tribute Summon "Dark Magician". "Sangan’s" effect is Chain Link 1 and "Witch of the Black Forest’s" effect is Chain Link 2. The effect of Player B's "Doomcaliber Knight" is chained, and it will negate "Witch of the Black Forest's" effect.
Example 2: Player A and Player B have "Goldd, Wu-Lord of Dark World" in their hand and Player A controls "Doomcaliber Knight". Player A activates "Card Destruction". When both copies of "Goldd, Wu-Lord of Dark World" are discarded, their effects start a Chain. Player A is the turn player, so his "Goldd, Wu-Lord of Dark World" is Chain Link 1 and Player B's is Chain Link 2. "Doomcaliber Knight's" effect is chained, and it will negate Player B's "Goldd, Wu-Lord of Dark World".
Example 3: Player A's "Giant Rat" is destroyed in battle and sent to the Graveyard while she has "Green Baboon, Defender of the Forest" in her hand and "Doomcaliber Knight" is face-up on the field. Player A can activate "Giant Rat" and/or "Green Baboon, Defender of the Forest's" effect. If she activates both effects, she chooses the order the effects are placed onto the Chain, and "Doomcaliber Knight" will negate the effect that is placed highest on the Chain. If "Green Baboon, Defender of the Forest" is Chain Link 1 and "Giant Rat" is Chain Link 2, "Doomcaliber Knight" will negate "Giant Rat".
Example 4: If "Sangan" is Tributed to Tribute Summon "Raiza the Storm Monarch" while "Doomcaliber Knight" is face-up on the field, "Sangan's" effect is Chain Link 1 and "Raiza the Storm Monarch's" effect is Chain Link 2. "Doomcaliber Knight's" effect is chained, negating "Raiza the Storm Monarch's" effect and destroying it.
Example 5: Player A's "Sasuke Samurai #4" attacks Player B's "Neo-Spacian Grand Mole" while "Doomcaliber Knight" is face-up on the field. "Sasuke Samurai #4's" effect is Chain Link 1 and "Neo-Spacian Grand Mole" is Chain Link 2. "Doomcaliber Knight's" effect is chained, and it will negate and destroy "Neo-Spacian Grand Mole".