Let's break this effect down into its component parts:

1. You want a mind shield. (Mind ••)
2. You want a contingent spell effect (Time •••, potentially Entropy ••• if the ST requires) that perceives when a mental attack connects with you (Mind •) and then releases another spell that either does psychic damage (Mind •••) or creates a psychic landscape that constrains the attacker's consciousness (Mind ••••) or forges a link to allow later magickal attacks (Correspondence ••)

So, what I see here is a Mind 3, Time 3 effect that could be boosted any number of ways. You'd want to allocate successes to the various aspects of the spell: the strength of the shield, how long the shield is up, how many times the shield's defenses can "go off," the damage that the blast inflicts, or the length of time the trap "holds" the target. I'd want to prepare it with as many advantages as I could, but once it's up, it's a nasty surprise for an attacker.

Let's break this effect down into its component parts:

1. You want a mind shield. (Mind ••)
2. You want a contingent spell effect (Time ••••, with a potential Entropy ••• add-on) that perceives when a mental attack connects with you (Mind •) and then releases another spell that either does psychic damage (Mind •••) or creates a psychic landscape that constrains the attacker's consciousness (Mind ••••) or forges a link to allow later magickal attacks (Correspondence ••)

So, what I see here is a Mind 3, Time 4 effect that could be boosted any number of ways. You'd want to allocate successes to the various aspects of the spell: the strength of the shield, how long the shield is up, how many times the shield's defenses can "go off," the damage that the blast inflicts, or the length of time the trap "holds" the target. I'd want to prepare it with as many advantages as I could, but once it's up, it's a nasty surprise for an attacker.