How to use

CanBlockAsThoughtItHadShadowEffect

in

mage.abilities.effects.common

@Override
public CanBlockAsThoughtItHadShadowEffect copy() {
  return new CanBlockAsThoughtItHadShadowEffect(this);
}

public HeartwoodDryad(UUID ownerId, CardSetInfo setInfo) {
  super(ownerId,setInfo,new CardType[]{CardType.CREATURE},"{1}{G}");
  this.subtype.add(SubType.DRYAD);
  this.power = new MageInt(2);
  this.toughness = new MageInt(1);
  // Heartwood Dryad can block creatures with shadow as though Heartwood Dryad had shadow.
  this.addAbility(new SimpleStaticAbility(Zone.BATTLEFIELD, new CanBlockAsThoughtItHadShadowEffect(Duration.WhileOnBattlefield)));
}

public WallOfDiffusion(UUID ownerId, CardSetInfo setInfo) {
  super(ownerId,setInfo,new CardType[]{CardType.CREATURE},"{1}{R}");
  this.subtype.add(SubType.WALL);
  this.power = new MageInt(0);
  this.toughness = new MageInt(5);
  // Defender
  this.addAbility(DefenderAbility.getInstance());
  // Wall of Diffusion can block creatures with shadow as though Wall of Diffusion had shadow.
  this.addAbility(new SimpleStaticAbility(Zone.BATTLEFIELD, new CanBlockAsThoughtItHadShadowEffect(Duration.WhileOnBattlefield)));
}

public AetherflameWall(UUID ownerId, CardSetInfo setInfo) {
  super(ownerId, setInfo, new CardType[]{CardType.CREATURE}, "{1}{R}");
  
  this.subtype.add(SubType.WALL);
  this.power = new MageInt(0);
  this.toughness = new MageInt(4);
  // Defender
  this.addAbility(DefenderAbility.getInstance());
  // Aetherflame Wall can block creatures with shadow as though they didn’t have shadow.
  this.addAbility(new SimpleStaticAbility(Zone.BATTLEFIELD, new CanBlockAsThoughtItHadShadowEffect(Duration.WhileOnBattlefield)));
  // {R}: Aetherflame Wall gets +1/+0 until end of turn.
  this.addAbility(new SimpleActivatedAbility(new BoostSourceEffect(1, 0, Duration.EndOfTurn), new ManaCostsImpl("{R}")));
}