How to use

ManaTypeInManaPoolCount

in

mage.abilities.dynamicvalue.common

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

public OmnathLocusOfMana(UUID ownerId, CardSetInfo setInfo) {
  super(ownerId, setInfo, new CardType[]{CardType.CREATURE}, "{2}{G}");
  addSuperType(SuperType.LEGENDARY);
  this.subtype.add(SubType.ELEMENTAL);
  this.power = new MageInt(1);
  this.toughness = new MageInt(1);
  // Green mana doesn't empty from your mana pool as steps and phases end.
  this.addAbility(new SimpleStaticAbility(Zone.BATTLEFIELD, new OmnathRuleEffect()));
  // Omnath, Locus of Mana gets +1/+1 for each green mana in your mana pool
  DynamicValue boost = new ManaTypeInManaPoolCount(ManaType.GREEN);
  this.addAbility(new SimpleStaticAbility(Zone.BATTLEFIELD, new BoostSourceEffect(boost, boost, Duration.WhileOnBattlefield)));
}