Each of those creatures doesnt untap during its controllers next untap step
Since Helga snowballs so fast, you're likely to become the main enemy very quickly, so you'll be targeted more than your opponents.
You'll definitely want to include several ways to remove her from combat or prevent damage so that she can safely swing before doing her best Cowardly Lion impression when something big blocks her
It goes infinite with Niv-Mizzet, Parun (hands down the strongest Izzet combo) but cards like Nekusar, the Mindrazer and Ghyrson Starn, Kelermorph make excellent use of this blue enchantment
Esper Sentinel Speaking of staples, heres Esper Sentinel
Cards that benefit from playing from exile, like Vega, the Watcher, and those with foretell or plot mechanics complement this strategy by maximizing the value of spells that return to the battlefield after a delay