Magnetic Web is a rare Artifact card from Tempest (TMP), collector number 295. Current market price: $0.66, TCGplayer market prices via Scryfall.
If a creature with a magnet counter on it attacks, all creatures with magnet counters on them attack if able. Whenever a creature with a magnet counter on it attacks, all creatures with magnet counters on them block that creature this turn if able. {1}, {T}: Put a magnet counter on target creature.