Place of supply shall be location where the event is actually held i.e. Karnataka (in present case).

As per 12(7) IGST Act :

If recipient is registered than location of such person, otherwise location where the event is actually held.

That is in case of organisation of event.
In your case, it is admission to an event.

Extract of Section 12 of IGST Act 2017:

(6)The place of supply of services provided by way of admission to a cultural, artistic, sporting, scientific, educational, entertainment event or amusement park shall be-  the place where the event is actually held or where the park or such other place is located.

In our case, thew Place of supply shall be Karnataka(Bangalore).

Hope it helps.

Kindly refer the Section 12(7) also ....
Yes iam very much agree with Mr. Sandeep Tiwari , in case "Admission to an Event , Section 12(6) Will Applicable.

Hence if 12(7) IGST is applicable , then POS will be the location of Recepient (Registered)
And In case if 12(6) is applicable , then POS will be the Location of event organised