Helix of Insight

Helix of Insight enters the battlefield tapped.
Whenever a player casts a spell, put a charge counter on Helix of Insight.
{4}, {t}, Sacrifice Helix of Insight: Draw X cards or counter target spell with converted mana cost X or less, where X is the number of charge counters on Helix of Insight.
Only one helix can cause such an increase of knowledge.