Counterspell is the skill and ability to use magic to disrupt and dispell incoming magic. When you cast counterspell, you roll a contested spell check against the caster casting the spell. You must use a spell slot of level 3 and above when casting counterspell and their spell slot is used regardless of result.
If there is a level difference in the counterspell vs the spell, the one with the higher level gains a +2 in spell level differential. The level difference refers to the spell splot being user, so a heightened spell using a 2nd level spell slot being heightened to overcast as level 3 will still count as a 2nd level spell.
You can prepare a counterspell with an action. When you prepare a counterspell, for the next minute you can cast Counterspell. Once you casted counterspell, you must use prepared counterspell again. If you cast prepare counterspell and do not cast counterspell, you must select a spell spot to lose that is valid(level 3 and above). However, you can choose the level whenever you actually cast counterspell.
Counterspell is counted as casting a spell. However, it’s origin is based on which caster are you casting the spell as.
It’s stats are as follow
Counterspell
100ft range
V, F
As a reaction to a spell being casted after having used prepare counterspell in the past minute, you can cast counterspell. The spell must have either to V, M or F component or take at least 2 actions to counterspell. You must be able to physically see the spell caster or be in range, or see the spell being casted to be able to counterspell. For example if you are unaware of a spell being casted or are ambushed by a spellcaster, even though technically you can see the spellcaster, you cannot counterspell. For purpose of this, the GM can create stealth vs perception checks in certain situations
Roll as per the counterspell rules when casting counterspell:
When you cast counterspell, you roll a contested spell check against the caster casting the spell. You must use a spell slot of level 3 and above when casting counterspell and their spell slot is used regardless of result.
If there is a level difference in the counterspell vs the spell, the one with the higher level gains a +2 in spell level differential. The level difference refers to the spell splot being user, so a heightened spell using a 2nd level spell slot being heightened to overcast as level 3 will still count as a 2nd level spell.