Rule Descriptions - Phase Spiders and the Combat Sequence

[I'm deep in the process of writing my own version of the OD&D rules.  I'm also running a monthly campaign to play-test through the rules and find things that are missing or broken in non-obvious ways.  This post is about one of those things.]

The party of adventurers recently ran up against a group of Phase Spiders inhabiting part of some ruins the party was hired to investigate and "make safe".  I used phase spiders for a couple of reasons: I had not used them yet in the campaign and they would produce a solid challenge for the PCs.  I kinda knew how phase spiders work, so I expected things to be interesting.  Unfortunately, it was nearly a roadblock instead of interesting.

Once the combat started, I looked to see how the rules handled their phase ability.  What it said was:

"When attacking or being attacked, the phase spider can shift out of phase with its surroundings, bringing itself back only when it is ready to deliver its poisonous bite."

There are several problems here.  First, does this mean that once combat starts, phase spiders are always out of phase, except when they roll for their attack?  If so, this is very broken as:  

"When out of phase they are impervious to nearly all forms of attack, although a Phase Door spell will cause one to remain in phase for 7 melee rounds.  Oil of Etherealness and Armor of Etherealness also put their wearers into the same phase as this monster when it shifts out of phase."

If that is not what it means, when do they phase in and out?  Is there a time limit between going from one state to the other?  How are the PCs expected to deal with this?

So I had to adapt this to something reasonable.  To explain what I did, you need to know some about how combat works in my rules.  I'm using the combat sequence from Philotomy's Musings, which means a modified version of the one from Chainmail.  It provides more options for movement and shooting/casting than the "I go - You go" method that most RPGs use now.  Here is the combat sequence for Adventures in the Green:

Combat Sequence

1. Initiative: Both sides roll 1d6 for initiative; high roll wins.
2. Missile/spell: In initiative order, both sides may fire missiles, cast spells, etc.
3. Movement: Side with initiative moves up to half move
4. Movement: Side without initiative moves up to half move
5. Missile/spell: In initiative order, both sides may fire missiles, cast spells, etc.
6. Movement: Side without initiative moves the remaining half move
7. Movement: Side with initiative moves the remaining half move
8. Missile/Spell: Unengaged combatants may fire missile, cast spells, etc.
9. Melee: Engaged combatants fight one round of melee.

Spell casters can only cast one spell per combat round, but there are three point where they can choose to cast.  Same with ranged fire (unless they do not move and get a second shot).  This method also means that those with initiative have the option of running away or cutting of those who try to run away, as those with initiative get the first and final moves.  Also, there are no attacks of opportunity, once you are in melee combat, you are pinned there until your opponent dies or you do [there are some options here, but too much detail for this discussion].

So back to phase spiders.  Phase spider can shift out of phase as a half-move equivalent.  When they attack in Melee, they phase back in and attack as one attack.  This lets them attack but leaves them vulnerable until their next Movement, when they can go out of phase again.  With their next Movement in step 3 of the sequence, they are vulnerable to melee attacks that come after them in initiative and the first spell casting step of the next combat round.

As OD&D does not have a Hold Action possible action, opponents cannot simply wait to attack and therefore have a narrow but usable window of opportunity.  This leads to opponents wanting to lose initiative to they can make their melee attacks after the spiders phase back in as part of their attack.  Spellcasters using quick spells [1st and 2nd level, which have no delay] can attack in the first Missile/spell step (step 2).  This gives PCs tactical options, which I consider important.  Also, spiders out of phase do not pin combatants in place, so opponents can flee if they chose to do so (although phase spiders are very fast when out of phase with a 15" movement).

The next issue was the "poisonous bite."  I decided that phase spiders have a paralytic poison.  This seems more in line with Level 4 monsters.  Save versus poison after being bitten or become paralyzed.  They will wrap you up after combat is over and eat you later.  The poison is probably long acting, so 1d6 hours seems reasonable, although a Cleric with access to the 4th-level spell Neutralize Poison will cure the paralysis.

That's it for this topic.  I'll post more as I find things to discuss/share.  Let me know if you have any questions about the rules or how they deal with something.

Later!