When you partner is leading, if you are asked to do something you REALLY don't want, let your partner know that this goes one step too far for you.
It's very healthy to have this "veto" right so that you feel totally secure in a tantric session.
As a general guideline, I would encourage you to use your veto right only in very rare, extreme cases.
Very often, a new tantric idea might stretch a bit your comfort zone. However, dare to experiment.
As soon as you try, you will notice that you might actually like it a lot.
If your partner is leading, really let go of trying to direct.
PLAY THE GAME!
ACCEPT THAT YOUR PARTNER IS IN CHARGE FOR THIS SESSION!
Having this attitude will let them feel that you trust them and immensely energize your tantric sex play.
It will give power, trust and confidence to your tantric sex couple and give you space to experiment.