Guild Wars 2

I was thinking about siege in wvw and what some interesting counter-siege equipment could be.
1) Introduce golem mastery. Remove the shield bubble from golems and instead make it a rank 5 in golem mastery. Reasoning: Golems already have a metric craptonne of health and having shield bubbles on top of that makes counter-siege difficult.
2) Rework ballista mastery. This is not (really) an anti-infantry weapon, and as such spread-shot is a terrible skill. This is much more effective as an anti-siege weapon. Introduce a new skill: penetrating bolts. Bolts are unblockable and ignore seige bubble.
3) Introduce a new siege equipement: siege-bubble generator. Costs 40 supply. It has two skills: i) Slow time. Lasts 5? seconds on a 30? second recharge. Increases the recharge on ram abilities by 66% and reduces golem attack speed by 50%. ii) generate siege bubble. Lasts 3 seconds on a 30 second recharge.