2010-11: Tomas Havlin skated for the Bili Tygri Liberec U16 team in the Czech Republic as a 14-year-old. In 27 games he scored 1 goal with 1 assist and was +10 with 26 penalty minutes.
2011-12: Havlin played for the Bili Tygri Liberec U18 and U16 teams and skated for the Czech U16 team. In 22 games with Liberec, including three playoff games, he had 6 assists with an even plus/minus and 14 penalty minutes. Havilin scored 7 goals with 13 assists and was +38 with 61 penalty minutes in 34 regular season games for the Bili Tygri U16 team and was minus-2 with 2 assists and 8 penalty minutes in five playoff games. In 12 games with the Czech U16 team he scored 1 goal with 4 assists and was +2 with 33 penalty minutes.
2012-13: Havlin appeared in ten games with the Bili Tygri Liberec U20 team. He spent most of the season with the Bili Tygri U18 team and played in 20 games for the Czech Republic U17 team — including participating in the Europe Youth Olympic Festival. He had 1 assist and was minus-2 with 10 penalty minutes in U20 play. Havlin scored 1 goal with 11 assists and was +11 with 82 penalty minutes in 35 regular season games for the Bili Tygri U18 team and was +2 with 1 assist and 2 penalty minutes in five playoff games. In 20 games with the Czech U17 team, including three games at the EYOF, he scored 1 goal with 4 assists and was +1 with 12 penalty minutes.
2013-14: Havlin made his pro hockey debut — skating in 18 games on loan to HC Benatky and Jizerou in the Czech second division — and played for the Bili Tygri Liberec U20 and U18 teams. He represented the Czech Republic in the 2014 U18 World Junior Championship. Havlin scored 1 goal with 1 assist and was minus-7 with 16 penalty minutes for HC Benatky. In 40 games, including four playoff games with the Bili Tygri U20 team, he scored 3 goals with 12 assists and was +6 with 49 penalty minutes. Havlin played for the Liberec champion U18 team and in 11 games scored 2 goals with 4 assists and was +4 with 37 penalty minutes. In seven games for the silver medal-winning Czech U18 team at the WJC he was +2 with no points nor penalties. Havlin was ranked 117th amongst international skaters in the final CSS rankings.
Havlín is one of the bigger surprises in Czech hockey this past season. The 6-foot-2, two-way defender is as versatile as they come. He can use his body to stop opponents, but has also become smarter with his stick. Havlin can also make big offensive plays, especially with his shot, which has turned into a lethal weapon. Defense is the area of his game where Havlín excels, however, and some games he looks like a brickwall out there.