Clive, Idealistic Knight

Whenever another Human creature enters the
battlefield under your control, Clive, Idealistic
Knight adds {w} to your mana pool. Spend this
mana only to cast a Knight or Soldier spell.
{t}: Target creature named "Mathilda, Legendary
Knight" gains +X/+Y, Indestructible and
Hexproof until end of turn, where X is Clive,
Idealistic Knight's Strength and Y is Clive,
Idealistic Knight's Toughness.