Great ideas. However, pip cost does not make them useful at all. Daybreak would be useful to cast a cleanse or shatter daybreaked round before hit round but it would require 4 power pips, thus even with max hits and using 0 pip cleanse or a blade, you are very limited on hits one could use. Shatter would be totally unusable since you would need Seven pips to preload a shatter 5.5 with mastery which leave you almost no pips to hit the next round. For example, to use heal (rebirth or pixie) with a daybreak heal boost, you would need enough pips so that you could just cast heal twice in a row.
Nightbreaker is even worse since you will generally want to heal or hit after casting a spell but nightbreak prevents you from boosting the hit with gargantuan, epic etc or using a tc hit after.
This can be solved by lowering the pip cost of the daybreak itself. Understand you are already giving up a round of casting to just use the break. However, lowering the cost would actually allow you to use daybreak at least when it would actually be usable (a hit or heal you would want to use). Anyhow, these spells are an interesting addition, just need to think how they might actually be used. There is very little use at that pip cost.
