One by one the mages take their spots in the chairs that have been set out for them against the far wall of the study. Penrose continues to watch the swinging crystal for a minute or so, and then directs his attention to his students.
"You've all come far these last couple of months. You can do in a few moments what used to take you hours." Penrose scratches idly at the rash on his hand. "But you're doing simple magic. Tricks. Your spells don't last more than a few minutes, and don't affect more than a small area or a single target." Each of the students knows that they could potentially do more, but it would be extraordinarily difficult.
In rules terms, all mages are capable of casting spells with modified duration and target factors. If you reference page 118 of the core Mage: The Awakening rulebook you'll find multiple ways you can modify spells. You can increase the potency of a spell, making it more difficult to dispel. You can increase the number of targets, allowing you to affect multiple people or things with a single casting. You can increase the radius of an area spell, allowing you to target a larger area with a spell. You can increase the duration of a spell, making it last longer (note that you can use advanced duration factors if you have more dots in an arcanum than are required to cast a spell).
Doing any of these things imposes dice penalties. For example, if Penrose wished to cast Eyes of the Matrix (page 165) so that if affected each of four students, and do so with a single spell (and therefore only have one instance of the spell count against the max number of spells he can maintain at once, rather than four), he would cast the spell as normal but with a -4 dice penalty. Needless to say this is a significant penalty.
"Chance," Penrose gestures at her, "cast a spell that provides yourself with the mage's sight. But make it last..." Penrose thumbs the blade of the gleaming sword that's been on his table both times his students have visited. "Make it last at least an entire day." Chance nods and concentrates in an attempt to cast the spell.
Chance has 2 dots in the Time Arcanum, more than the 1 required for Temporal Eddies (page 258), the Time mage sight spell, allowing her to use the advanced duration factors described on page 119. She has a Gnosis of 1 and Time 2, for a pool of 3. Under the advanced duration factor table we see that casting a spell that normally has a prolonged (one scene) duration with an increased duration of 24 hours incurs a -2 dice penalty. So Chance is down to 1 die.
She rolls 0 successes on 1 die, and the spell fails.
Penrose doesn't seem surprised. "It's not easy. But what if instead of casting a spell in moments, you took the hours you used to?"
The vast majority of the time you'll be casting spells as instant actions, as you've been doing. Occasionally it will be in your benefit to cast spells ritually. Ritual magic takes time (see just how much time by referencing the table on page 121), especially if you have a low Gnosis, but the benefit is that you accumulate successes over a period of time rather than trying to get them all on one roll. You can change the way your spell works with ritual magic just like normal, by referencing page 120. There you'll see that with ritual magic you don't take dice penalties - instead the number of successes needed is increased. That Eyes of the Matrix spell Penrose was going to cast in the example? Rather than taking a -4 penalty to a single roll, he now needs two more successes than normal, and he can keep casting until he has the successes he needs.
One thing to keep in mind is that you have to announce what parameters you're aiming for when you start the spell. You can spend a point of Willpower at any time to cast a spell using the number of successes already scored rather than continuing to accumulate more.
"Each of you will have six hours," says Penrose, ignoring the panicked looks his students exchange, "to cast a spell. The spell needs to last 24 hours and be at least somewhat resistant to dispelling." "Somewhat resistant to dispelling" refers to an increased potency. "Those of you who manage it will get a drink of tass." Tass is mana in its material form. Penrose is miserly with the tass that his hallow provides, only occasionally giving his students any in water form.
"Begin."
Everyone pick a spell with a prolonged duration to cast and choose what level of potency you're aiming for (the 24 hour duration is required, as is at least potency 2 - you can aim for a higher potency if you're feeling bold, though it will cost you a point of Willpower if you haven't reached the target successes in six hours). It's recommended you try a level 1 spell of an arcanum that you have 2 dots in, so that you can make use of the advanced duration factors. You can spend Willpower up to twice (once per roll) to add dice, whether you do is up to you.