using System;
using System.Collections.Generic;
using System.Linq;
 
public class Test
{
	public static void Main()
	{
		var mainList = new List<string>
            {"Reset", "Set", "Test", "Test", "Reset", "Test", "Test"};
        var i = 1;
        var result = mainList
            .Select(str =>
            {
                if (str == "Reset") i++;
                return new {str, i};
            })
            //  ^^ Above I make partitions by `i`; that `i` will change by watching a `Reset`
            .GroupBy(g => g.i)
            .Select(g => g.Select(c => c.str).ToList());
        	// then I just group by `i` as partition then removing it from results.
 
        foreach (var item in result)
        {
            foreach (var str in item)
            {
                Console.Write($"{str}, ");
            }
            Console.WriteLine();
        }
	}
}

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