Tengu format ruling
B.E.S. Covered Core

Card effect (current official text)When this card is Normal Summoned, put 2 counters on it. This card cannot be destroyed by battle. If this card attacks or is attacked, at the end of the Damage Step toss a coin and call it. If you call it wrong, remove 1 counter. If this card battles without a counter, destroy it at the end of the Damage Step.
Rulings
(1) When this card is Normal Summoned, put 2 counters on it. (2) This card cannot be destroyed by battle. (3) If this card attacks or is attacked, at the end of the Damage Step toss a coin and call it. If you call it wrong, remove 1 counter. (4) If this card battles without a counter, destroy it at the end of the Damage Step.
- The (1) Trigger Effect is mandatory, it activates & resolves on the field.
- If this card's effects are negated, the counters placed by this effect are removed.
- The (2) Continuous Effect applies while this card is face-up on the field.
- The (3) Trigger Effect is mandatory, it activates & resolves on the field.
- This effect activates in Substep 7 - End of the Damage Step.
- The (4) Trigger Effect is mandatory, it activates & resolves on the field.
- This effect activates in Substep 7 - End of the Damage Step if this card had no counter on it at the start of the Damage Step.
- If "B.E.S. Covered Core" battles a monster, and afterwards you lose the coin toss (for the (3) effect), so that "B.E.S. Covered Core" now has no counters, it is not destroyed. Because it still had a counter during damage calculation.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Tengu forum — sourced change requests get reviewed.