The Siege Technician has 0 strength, so it adds nothing to the Siege row by itself. What it does have is Medic: when you play it, you revive a non-hero unit from your discard pile and play it at once. Torrential Rain is the card to fear here, since it sets every non-hero Siege unit to 1 strength until Clear Weather clears it.
Buy it from the innkeep of the Golden Sturgeon in Novigrad. With Hearts of Stone, the elven merchant at the circus camp near Carsten sells it as well.
Plan a Remastered build: skill trees, mutagens, gear and a shareable build image.
Pick a potion, decoction or bomb and see every ingredient you need.
Answer the key choices and find out which Witcher 3 ending you will get.
Every location, quest and monster in the first region on one map.
The Wolf School's hidden valley: the keep, the Bastion, caves and treasure.
Tick off every school gear diagram and crafted piece, with diagram locations.
Search any monster and see the right oil, Signs and bombs.
