2009-10: Luca Fazzini played in Switzerland's Elite Novizen U17 league as a 14-year-old and dominated for Lugano at the U15 level. He scored 20 goals with 12 assists and 46 penalty minutes in 31 regular season games. Lugano reached the Elite Novizen finals against ZSC Lions and Fazzini scored 8 goals with 4 assists and 6 penalty minutes in 12 playoff games. He scored 26 goals with 14 assists and 10 penalty minutes in 11 games with Lugano's U15 team.
2010-11: Fazzini scored at a point-per-game pace in Switzerland's Elite Junior A League — splitting the season between the U20 and U18 levels — and played for Switzerland's U16 team. He scored 10 goals with 5 assists and 4 penalty minutes in 15 games, including one playoff game, for Lugano's U20 team. Fazzini scored 16 goals with 6 assists and 113 penalty minutes in 17 regular season games for the Lugano U17 squad. Lugano lost to EHC Kloten in the playoff quarterfinals. Fazzini scored 4 goals with 4 assists and 2 penalty minutes in four playoff games. He scored 6 goals with 3 assists and 6 penalty minutes in 13 games for Switzerland's U16 team.
2011-12: Fazzini split the season between Lugano's Elite Junior A and Elite Novizen squads and played for Switzerland's national team at the U18 and U17 levels in international play. He scored 19 goals with 9 assists and 16 penalty minutes in 27 games for seventh place Lugano's U20 team. Fazzini scored 39 goals with 13 assists and 69 penalty minutes in 21 games for the Lugano U17 team. Lugano won a five-game series with EV Zug before falling to HC Davos in the Elite Novizen semifinals and defeated the SCL Tigers in the third place game. Fazzini scored 7 goals with 6 assists and 33 penalty minutes in seven playoff games. He scored 6 goals with 1 assist and 6 penalty minutes in 12 games for Switzerland's U18 team and had 8 goals with 2 assists and 12 penalty minutes in seven games for the Swiss U17 team.
2012-13: Fazzini played 27 games, including six playoff games, for Lugano in Switzerland's National A League and represented Switzerland in the 2012 World Junior A Challenge and the 2013 U18 World Junior Championship. He scored 2 goals with 1 assist and was +4 with 2 penalty minutes in 21 regular season games for sixth-place Lugano and was -1 with no points and 2 penalty minutes in the National A playoffs. Fazzini scored 16 goals with 9 assists and 69 penalty minutes in 15 regular season games and scored 1 goal with 1 assist and 2 penalty minutes in three playoff games for Lugano's U20 team. He scored 4 goals with 1 assist and 4 penalty minutes in five games at the WJAC and had 5 assists and 2 penalty minutes in five games at the U18 WJC. Fazzini was ranked 81st amongst European skaters in Central Scouting's final rankings but was not selected in the 2013 NHL Draft.
2013-14: Fazzini saw increased ice time in his second National A League season with Lugano and played a key role as the club's U20 team was the runner-up in the Elite Junior A League. He scored 6 goals with 2 assists and was an even plus/minus with 8 penalty minutes in 35 games for Lugano, including one National A League playoff game. Fazzini scored 14 goals with 16 assists and had 16 penalty minutes in 15 regular season games for the Lugano U20 team. He scored 9 goals with 4 assists and 6 penalty minutes in ten playoff games as the club, after finishing fifth during the season, reached the finals against Bern. Fazzini was ranked 49th amongst European skaters in Central Scouting's final rankings prior to the 2014 NHL Draft.