The Fruit of Saint Tree

Card Effects
[LV1][LV2] (Opposing Attack Step) When your Life is reduced by opposing Spirits, put a core from the Void to your Reserve. [LV2] (Opposing Main Step) When the opponent uses Magic cards for two times or more, after the effect resolves, end the opposing Main step.

Card Effects (JP/日本語)
Lv1・Lv2『相手のアタックステップ』相手のスピリットによって自分のライフが減ったとき、ボイドからコア1個を自分のリザーブに置く。 Lv2『相手のメインステップ』相手がマジックカードを2回以上使用したとき、その効果発揮後、相手のメインステップを終了する。

Sets

BS17 (Common)

Illust: Kobayashi Yuuya
EN Flavor:
There is a treasured tree fruit in Wind Shield that is said to be able to restart a heart once stopped. In 100 years, only 5 such precious fruits would mature. Manaka was entrusted with two of them, all so he could vanquish the Vanity Deities.
—Authentic History: Chronicles of Manaka, Year 643—
JP Flavor:
1度だけ止まった心臓を動かしてくれるという、風楯で財宝とされる樹の実がある。100年に5つしか実らないという貴重なものを、マナカは2つも託された。すべては虚神を倒すために。
―正史マナカ伝 643年の章―

Rulings
1) If you negated the opposing Magic via Ice Wall when they used Magic cards for the second time in the Main Step, you can't activate this Nexus' LV2 effect, as the Magic effect can't be activated, and the "after the effect resolves" part of this Nexus' LV2 effect can't resolve.

Anime Appearances
Battle Spirits Heroes