Can I play it on the repeat on hard bargain to counter spell the deny?

No, you cannot use the Repeat execution of Hard Bargain to counter Defy.

Here is why this interaction does not work as you described, based on the rules for Repeat and the Chain:

1. Repeat is decided when the card is played

According to Rule 820.1.c.1 and Rule 820.1.d, Repeat is an additional cost that you must choose to pay at the moment you play Hard Bargain from your hand. You cannot decide to pay it later, nor can you wait to see how the opponent responds to the first instance before deciding to activate the second.

2. The Chain is resolved LIFO (Last-In, First-Out)

When you play Hard Bargain, it goes onto the chain. If your opponent then plays Defy in response, Defy is placed on top of Hard Bargain.

• Chain (bottom to top): [Hard Bargain] → [Defy]

Because Defy is on top, it resolves first. If Defy successfully counters Hard Bargain, Hard Bargain is removed from the chain and does nothing (Rule 425.1.a). It never gets a chance to resolve, so its effect (countering a spell) never happens.

3. Repeat does not create a second spell

Even if you pay for Repeat when you first play Hard Bargain, it remains a single entity on the chain (RiftJudge FAQ #10472). If your opponent plays Defy to counter that spell, they are countering the entire instance of Hard Bargain, including the repeated effect. You cannot "split" the executions to use one against the spell you are targeting and one against the Defy that is countering you.

Summary: You must choose to Repeat when you first play Hard Bargain. If your opponent plays Defy in response, it will resolve first and counter your Hard Bargain before it has the chance to resolve its own effects.