Helga has power 4 or greater and does not have summoning sickness.
Steps
Activate
Helga by tapping it, adding at least ({U} magic symbol) ({U} magic symbol) ({U} magic symbol) ({U} magic symbol) that can only be spent to cast creature spell with mana value 4 or greater or with ({X} magic symbol) in their mana cost.
Cast
Venser by paying its mana cost.
Helga and
Chakram Retriever trigger.
Resolve the
Helga trigger, causing you to draw a card, gain 1 life, and put a +1/+1 counter on
Helga.
Resolve the
Chakram Retriever trigger, causing you to untap
Helga.
When
Venser enters the battlefield, it triggers, returning it from the battlefield to your hand.
Repeat.
Results
Infinite card draw.
Near-infinite lifegain.
Near-infinite lifegain triggers.
Near-infinite ETB.
Infinite draw triggers.
Near-infinite storm count.
Near-infinite LTB.
Near-infinite +1/+1 counters on
Helga.
Near-infinite colored mana that can only be spent to cast creature spells with mana value 4 or greater or creature spells with X in their mana cost.