Wording for the "4 activations" rule:
Players are restricted from activating one or more instant effects in the special ability on the same card more than 4 times in a turn.
This rule will be added to the next REG update, to be released 4/11/22.
The rule only applies to instant effects (draw, discard, banish, etc.), so it doesn't cause ongoing effects (protect, restrict, etc.) to potentially be inactive if the they would be a 5th activation. Since negate is both instant and ongoing, it does count as one of the activations.
The rule only applies to special abilities, so activating the star ability of a card does not count as one of the activations.
The usage of "one or more instant effects" allows multiple effects to activate together but only count as 1 activation, for cards with multiple abilities, like Life in the Son. However, each activation of triggered effect counts as its own activation, regardless of how many times the ability was triggered.
The rule applies to all effects on the card, not each effect separately. So a card like Treacherous Land gets 4 combined underdecks and draws, not 4 of each.
