REDU format ruling
Overdoom Line

Nearest-era rulings (Tengu, Sept 2011) — no REDU-specific archive exists.
Card effect (current official text)If a Plant-Type monster(s) is Special Summoned from the Graveyard to your side of the field: It gains 1000 ATK while this card is face-up on the field. Destroy this card during your 2nd End Phase after activation.
Rulings
- The ATK boost of "Overdoom Line" starts a Chain, but does not target.
- The text on "Overdoom Line" that destroys itself is not an effect, so "Royal Decree" etc. will not stop it from being destroyed.
- Plants that were Special Summoned before the activation of "Overdoom Line" do not receive an ATK boost when "Overdoom Line" is activated.
- Monsters that get an ATK boost from "Overdoom Line" keep the boost even if they become a Type other than Plant-Type.
- If a monster receives the ATK boost from "Overdoom Line" but is flipped face-down, it loses the boost, even if flipped face-up again while "Overdoom Line" is still on the field.
- You cannot activate "Overdoom Line" during the Damage Step.
- While "Imperial Custom" is active, "Overdoom Line" cannot destroy itself, so it will remain on the field. Its effect will also remain.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the REDU forum — sourced change requests get reviewed.