Reset reads "restore a unit to its base strength"
The only card that mentions deck builder is "Mandrake", which used to have a unique keyword, but now it's just a description which doesn't include the word "reset".
So, before it was 'reset to base power' for cards like spore and 'reset' for mandrake.
They changed it so that 'reset' means only the strength. It does not modify statuses, charges, timers etc. Mandrake, however, resets the card's strength AND is supposed to reinitialize the card: remove/restore statuses (if a unit is locked: unlock, if a defender is purified: give the status back), give back initial charges, reset timers and orders so you can even re-use them. It's a very strong card if used properly.