The summoner rolls their Magic skill, taking a penalty according to the level of the spirit:
Don’t forget that - per the Power Preparation rule (SWADE pg 140) - if a summoner concentrates for an entire round (taking no action, not moving, not being Shaken or Stunned), they can cancel up to 2 points of penalty to any power roll. This applies to practically all summoning done outside of combat and helps offset the penalties listed above.
Take a Drain resistance test on a natural 1 on the Magic die, as usual.
Summoned spirits last for (Spirit die type) hours and can do unlimited things for the summoner in that time. There is no concept of favours as used in spirit summoning in Shadowrun. Remote services - anything that takes the spirit more than (Spirit die type)×10 metres away from its summoner - use this time period up at 10× faster rate.
A summoner can dismiss a summoned spirit as a free action.
On a raise on the summoning roll, the spirit gains the Resilient power, and so it will be able to withstand an extra Wound before being disrupted. If the spirit already has the Resilient power, it is promoted to Very Resilient (two wounds) on a raise.
The spirit enters the world already materialised on the physical plane and can act immediately. In combat, they act on the same initiative card as their summoner. Mages can send mental commands to their summoned spirits as a free action and they can do that immediately after summoning.
By default, summoners can only have one lesser/common/greater spirit summoned at a time. This does not count as maintaining a power, so there is no ongoing penalty to the mage’s rolls. They can also keep one servant/watcher summoned.