Dortmund are fifth in the Bundesliga with two games left, having already secured their Champions League participation next season.
They also face Real Madrid in the June 1st final of Europe's top club competition, following Tuesday's 2-0 aggregate win over Paris St Germain.
Terzic, however, is determined that his side maintain their intensity levels, even if he rotates his squad.
"Through this rotation we not only keep the team physically and emotionally fresh but we also give chances to other players," Terzic told a press conference.
"Our season just got a bit longer and we want to keep the rhythm up. It is about what we have built up in the past weeks and us wanting to still achieve something big, and that cannot happen with us shifting down a gear.
"We want to make these weeks the best weeks of the season," he added.
Mainz, who last season snatched a 2-2 draw in Dortmund on the very last matchday to deny the Ruhr valley club the league title, are now battling to avoid relegation.
For Terzic, however, it will not be a case of payback.
"They did spoil our summer last year. But they did it fair and square. They had a say last season and did it well. Totally fair and intensive," he said.
"Now we have the chance to have an influence (on their situation)." Mainz are in 16th place in the relegation playoff spot, five points ahead 17th-placed Cologne.
More importantly for Terzic, the game marks the start of a three-week preparation towards the Champions League final.
"We celebrated our qualification to the final on the night and now we have to deal with the situation pragmatically," he said.
"Now a new preparation starts for the Champions League final with these remaining two Bundesliga matches."
