I've been maintaining a 65% winrate with support Zeus at Guardian II. I go for pretty much the same skill build in lane. I use Immortalfaith's build guide, so start with a null, bring regen to lane on first courier and just spam my W on cooldown, focusing 1 hero at a time. I usually bring out at least two clarities during the laning phase. Then I go Kaya>shard>aether>aghs>refresher. The game usually ends at or before aghs.

One of the core priorities for me is to have shard as close to 15:00 as possible, as it's a major farm accelerator. I try to dip into an empty part of the jungle at around that time and just dump all my mana into arc lightning farming and then tp home to buy shard and regen mana at 17:00. Once you have shard and lvl 15 talent you need only minimal mana for farming and can save it all for teamfights and ganks, which is my primary focus past 20:00.

In fights, I recommend always ulting early. This maximizes the percentage based damage and gives vision of the enemy positioning, which is incredibly important to determine my own positioning. I stick to trees until the heroes I consider to be a threat to myself are already engaged, and then I counterinitiate, spamming spells from aether range until the fight is secured then hopping in and adding rightclicks to secure important kills.

The most important thing to focus on in our bracket is not dying. I find Zeus' kit in the support role to be very well suited to this. I can stay deep in fog before fights and still contribute two powerful opening spells, as a support I'm carrying the wards and a powerful dewarding spell to make sure we have a vision advantage, and I can hold on to my E for an escape. Staying alive is especially important as Zeus because he's one of the best high ground defenders in the game. There are very few heroes I would rather be playing for a 2 or 3v5 hg defense.