Sunavalon Bloom (GFTP-EN026) [Ghosts From the Past]

When this card is activated: If you control a Link-4 or higher Plant Link Monster, negate the effects of all face-up monsters your opponent controls. During damage calculation, if your Plant Link Monster battles: You can make that monster gain ATK equal to the total ATK of all monsters it points to, until the end of this turn (even if this card leaves the field). You can only use this effect of "Sunavalon Bloom" once per turn. You can only activate 1 "Sunavalon Bloom" per turn.