Helga has power 4 or greater and does not have summoning sickness.
({RG} magic symbol) available.
Steps
Activate Helga by tapping it, adding at least ({R} magic symbol) ({R} magic symbol) ({R} magic symbol) ({R} magic symbol) or ({G} magic symbol) ({G} magic symbol) ({G} magic symbol) ({G} 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 Sparkcaster 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 Sparkcaster enters the battlefield, it triggers twice.
Resolve the first trigger, returning Sparkcaster from the battlefield to your hand.
Resolve the second trigger, dealing 1 damage to any target.
Repeat.
Results
Near-infinite damage.
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.