So I understand -1-1 counters on a creature reducing its toughness to 0 will not allow it to regenerate coming back. Is it the same thing as getting -4-4 perhaps until the end of turn? Thanks
Think of Regenerate only applying to damage.
Damage as in combat (you block his 5/5 with your 2/2 regenerate) or burn spells (Deal X damage to target creature, etc).
Toughness modifiers (-x / -x until end of turn or -1 counters, etc) cannot be regenerated since they aren't damage.
704.5f
If a creature has toughness 0 or less, it's put into its owners graveyard. Regeneration can't replace this event.
So it's the same..thought so thanks!