Thoughts on Bard Support Itemization - AP vs Tanky
After some playing and brainstorming with him on the PBE, I have some thoughts about how to build him for support.
Looking at his abilities, he has a grand total of .7 offensive AP scaling, and .2 - .45 heal scaling; his remaining two abilities are CDR only. This is below even Zilean status in regards to utilize AP. His passive is arguably the most damaging aspect, and it is only good for 1 auto every 11-9 seconds (but can burst for 2-3 hits).
I have stacked AP on him, and while it was reasonably effective in skirmishes and picks, it wasn't very practical during team-fights or in lane. This lead to thoughts about how to beef him up a little and rely on his high base damages rather than attempt to augment them.
One additional note: Rylias/Liandries are not applied with his passive-enhanced AA's.
TL;DR:
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If Fed:
Normal:

This focuses on getting 40% CDR to maximize his long CDs plus team-oriented items that help with map control. If fed, RoA/Banner are some offensive options to consider. If behind, just get tank.
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I tried Relic, but even with his passive, it was not even close to Thresh level, so I ditched this even though I liked the hp it gave.
I tried Spell Thief, but since his range is 500, he usually ended up taking more damage than he could inflict or heal every time he went to trade, plus the AP wasn't noticeable at all.
Honestly, Bard likes playing passive in lane, and is really good at preventing engagements on his Adc, a playstyle best suited for Coin. That, and the MS and sustain really go well with his lack of AP scaling.
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Bard has just enough AP ratios on him that if ahead, the AP and manna can be put to good use keeping the lead. The HP is still the most valued component of these items though. My inclusion of Banner is because with Bard's high tendency to roam, he can place an empower minion in a lane to do its work with ease. If this isn't something you'll use, then stick with the usual.
RoA is something to build if you really think you want an offensive item. If you are doing super well in lane and want an offensive item, this is the only one I'd recommend. Otherwise, stick with Randuins/Warmogs/whatever.
Why
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Because it's a tank item, and helps with map pressure, just like Banner does. With these two combined, you can pressure a 3rd lane and threaten a tower, despite he has zero tower-killing ability. Bard is mobile enough he can throw this up in a lane and force a response there while easily returning to the main group, forcing the enemy to respond.
Game-play:
Lane (2-16): Be passive, punish enemy attempts at aggression, maintain your flower garden near your tower, and just farm the lane. Freezing is good. When your adc backs for an item, go roam and pick up some charms, then back yourself: Do not leave lane while your adc is farming to pick up charms.
Mid-game (18+): Move your flower-garden to the jungle between mid and bot lanes, and keep up the wards. Start roaming too. Note that your Zhonya's ult has a stupid long (4000) cast range, so you can affect fights from miles away. Note that it has a flat travel speed, so plan accordingly.
Late-Game (35+) & team fights:
Focus on keeping lane pressure up. While Bard has zero waveclear, his
and/or
should give some assistance for this. Stay with your team as you are their tank and peeler (NOT ENGAGER: save your ult for your carries).
That's my thoughts on him. Feedback? I know he's not out yet, but now's a good time to discuss.